Tsugumi Aritomo was born on September 7, 2004, in Chiba Prefecture, Japan.
Her professional chronology begins before Sakura Gakuin.
In 2012, she won the grand prize in the Sanrio Puroland and Amuse “Asobinde! Audition.”
Official Amuse material for the audition described the grand-prize benefits as a period of Sanrio Puroland image-model activity together with access to Amuse training opportunities.
The audition should therefore be described carefully.
It was an important career starting point and is consistently connected with Aritomo's early entertainment path, but the prize itself should not be rewritten as a contractual guarantee that she automatically became a fully managed Amuse artist on the day she won.
The important point is that by childhood she was already working in front of cameras and within professional entertainment environments.
Before entering Sakura Gakuin, she accumulated television experience.
She appeared in the 2015 Nippon Television drama Gisou no Fuufu, commonly translated as Fake Marriage.
Secondary credit databases disagree about the exact episode count associated with her child-role appearance.
Because the original program's surviving public cast information is less specific than later fan databases, this profile records the drama credit without forcing a disputed episode total.
In 2016, she appeared as a younger version of Hayako in Fuji Television's Hayako-sensei, Kekkon Surutte Hontou desu ka?.
A child-cast report identifies her in episode four.
These early credits matter because they show that Aritomo did not arrive at Sakura Gakuin with no camera experience.
However, Sakura Gakuin demanded a different performance system.
She had to adapt from short-form acting and modeling work to synchronized choreography, ensemble singing, live MC work, weekly variety-style conversation, audience interaction and the long public-development format that defined the group.
On May 6, 2016, Aritomo was introduced at Sakura Gakuin 2016 Nendo ~Transfer Ceremony~ at Nakano Sunplaza Hall.
She entered as a sixth-grade elementary-school student.
Her transfer classmates were: Yuzumi Shintani, Momoe Mori, and Tsugumi Aritomo.
The three joined a nine-member returning group, creating a twelve-member 2016 school-year lineup.
Sara Kurashima became Student Council President.
Aiko Yamaide became Vice President.
Mirena Kurosawa became MC Chairperson.
Aritomo's early Sakura Gakuin character was immediately comfortable with humor.
Her public self-introduction included an unusual special skill: making a whistle-like sound with chikuwa, the tube-shaped fish cake.
The detail is minor in a conventional career résumé, but it captures something central about her Sakura Gakuin persona.
She was willing to commit to a strange bit without protecting herself from looking silly.
That willingness became useful in a group where variety skills, improvisation and comic courage were treated as part of the educational process.
Her most important extracurricular role began almost immediately.
During Tokyo Idol Festival 2016, she appeared as a provisional member of Sakura Gakuin's Purchasing Club.
The club was centered on merchandise promotion but performed that task as comedy and character entertainment rather than as a simple sales announcement.
Aritomo joined Soyoka Yoshida, who was already associated with the club.
At Sakura Gakuin Festival 2016, Aritomo was formally promoted into the unit.
The Yoshida–Aritomo pairing became the defining Purchasing Club lineup of the later Sakura Gakuin years.
Their segments combined product information, deliberately exaggerated salesmanship, comic argument and fast changes of tone.
They also made strong use of Kansai-style speech and merchant-character language.
Aritomo's instinct for reactions and Yoshida's established Purchasing Club identity complemented one another.
The result was not simply two members reading prices from a card.
The unit turned merchandise presentation into a recurring performance format.
At the 2016 school-year Song Archaeology class, Aritomo selected Hitoto Yo's “Hanamizuki.”
Song Archaeology required each member to research a song released before her birth, explain the personal or historical connection and then perform it a cappella.
The class exposed members without choreography or group vocal cover.
For Aritomo, it offered an early public example of the serious side that existed underneath the comic persona.
Sakura Gakuin 2016 Nendo ~Yakusoku~ was released on March 3, 2017.
It was Aritomo's first Sakura Gakuin annual album.
The 2017 school year placed her in the first year of junior high school.
Aiko Yamaide became Student Council President.
Megumi Okada became Talk Chairperson.
Momoko Okazaki became Ganbare!! Chairperson.
The weekly program Sakura Gakuin no Ganbare!! FRESH! Monday began in June 2017.
The program became especially valuable for Aritomo because it rewarded exactly the skills her public character was developing: quick reactions, impressions, jokes, mistakes that could be turned into material and the ability to respond when a segment stopped going according to plan.
Her comic identity was never based only on delivering prepared punch lines.
She often worked through facial expression, exaggerated movement and a willingness to become the target of the joke herself.
That style could make her appear carefree.
Comments from younger members later showed a more methodical side.
Miki Yagi, for example, remembered Aritomo as someone who could cheer her up through funny faces but who was also dependable and able to give detailed corrections in dance practice.
The contrast became important to understanding Aritomo's leadership.
She did not necessarily lead by adopting a solemn senior image.
She could keep the atmosphere light while still noticing technical problems.
The Purchasing Club continued throughout the year.
In 2017, the unit also participated in an Amuse Fes merchandise-introduction video connected with a large company-wide event.
Aritomo and Yoshida worked in the same comic sales format with appearances by senior Amuse artists including Perfume's Nocchi and Sakura Fujiwara.
The crossover placed the school-unit gag inside a broader professional Amuse environment.
At the 2017 school-year Song Archaeology class, Aritomo selected Elephant Kashimashi's “Kaze ni Fukarete.”
The choice continued the annual record of her music research and exposed singing.
Sakura Gakuin 2017 Nendo ~My Road~ was released on March 3, 2018.
In the 2018 school year, Aritomo advanced into the second year of junior high school.
Yuzumi Shintani became Student Council President.
Maaya Asou became Talk Chairperson.
Marin Hidaka became Hamidase!! Chairperson.
Kano Fujihira became Performance Chairperson.
Soyoka Yoshida became Education Chairperson.
Aritomo did not receive a council office that year, but her club identity remained unusually stable.
She continued the Purchasing Club with Yoshida.
The pairing was by then recognizable enough that the audience understood the rhythm before the joke fully developed.
That familiarity allowed the unit to play with expectation: a straightforward announcement could become an argument, a sales pitch could become a sketch, and a sketch could suddenly return to real merchandise information.
In October 2018, Sakura Gakuin announced Aritomo's participation in promotional activity for Bandai's Tamagotchi Meets.
The work included commercial / promotional-video activity and connected her individual visual presence with a major Japanese toy property.
At the 2018 school-year Song Archaeology class, held on March 3, 2019, Aritomo selected Koji Tamaki's “Melody.”
She explained that it was one of her father's favorite songs.
She connected the lyrics with her own feelings about Sakura Gakuin and about continuing in performance fields such as dance, acting and modeling.
The performance was memorable because she encountered a pitch problem and restarted.
Instead of allowing the error to destroy the presentation, she recovered and continued.
Afterward, she could also joke about the fact that a family-linked explanation resembled the story she had used in a previous year.
That combination—visible nervousness, recovery and humor after the fact—was characteristic of Sakura Gakuin's educational framing.
A performance did not need to be presented as flawless in order to be valuable.
Sakura Gakuin 2018 Nendo ~Life Iroasenai Hibi~ was released on March 3, 2019.
On May 6, 2019, Aritomo entered her final Sakura Gakuin school year.
Kano Fujihira became the ninth Student Council President.
Soyoka Yoshida became the second Ganbare!! Chairperson.
Tsugumi Aritomo became the second Hamidase!! Chairperson.
Momoe Mori became the sixth Talk Chairperson.
Aritomo inherited the Hamidase!! office after Marin Hidaka.
The title is difficult to translate with a single English word.
“Hamidasu” carries the sense of sticking out, exceeding a boundary, stepping outside a frame or refusing to remain neatly contained.
Within Sakura Gakuin, the office therefore represented more than simply “being eccentric.”
It encouraged a member to create energy by going beyond the safe or predictable response.
Aritomo's existing public identity made the appointment logical.
She already had years of experience using unusual facial expressions, impressions, physical comedy and sudden shifts of character.
The office gave those instincts a formal leadership context.
At the same time, her responsibility as one of four graduating seniors required her to support younger members rather than merely pursue her own comic moments.
The 2019 senior class was unusual because each of the four third-year junior-high members held a council title.
Kano handled the presidency.
Yoshida handled Ganbare!! responsibility.
Aritomo handled Hamidase!! responsibility.
Mori handled talk.
Their roles made visible four different styles of leadership rather than forcing one person to represent the entire graduating class.
During the year, Aritomo continued Purchasing Club activity with Yoshida.
That continuity gave the two a rare long-form subunit relationship inside Sakura Gakuin.
They had moved from provisional 2016 appearances to becoming senior members carrying an established club identity into the final year.
In October 2019, a second professional path began while all four graduating members were still enrolled.
On October 15, anonymous social-media accounts appeared for a group called @onefive.
At Sakura Gakuin Festival 2019 on October 19, the members were revealed as KANO, SOYO, GUMI and MOMO.
They were Kano Fujihira, Soyoka Yoshida, Tsugumi Aritomo and Momoe Mori.
Aritomo adopted the stage styling GUMI.
The quartet performed “Pinky Promise,” choreographed by MIKIKO, during the encore.
The digital single was released on October 20.
The name @onefive referred to the fact that the four were fifteen when the project began and to the phrase ichi-go ichi-e, the idea of valuing each encounter as something that may occur only once.
The “@” was also explained through the ideas “from us” and “from this place now.”
@onefive was not a standard Sakura Gakuin club.
It was revealed during a Sakura Gakuin event while its members were still students, but it was structured as a group able to continue after compulsory graduation.
That distinction became critical only months later.
Sakura Gakuin 2019 Nendo ~Story~ was released on March 3, 2020.
It included “Crossroad,” performed by the four graduating third-year junior-high members.
The planned final school-year events were then disrupted by the COVID-19 pandemic.
The Song Archaeology class and the conventional March graduation schedule could not proceed normally.
Consequently, Aritomo completed three documented public Song Archaeology selections during her Sakura Gakuin years rather than four.
@onefive also had to begin much of its early public development under restrictions.
The group released its first physical single, “Mada Minu Sekai,” on June 24, 2020.
Ordinary live audience growth was limited, so streaming, online events and remote communication became unusually important to the quartet's first period.
On August 30, 2020, Aritomo finally graduated from Sakura Gakuin with Kano Fujihira, Soyoka Yoshida and Momoe Mori in the no-audience streamed program The Road to Graduation 2019 Final.
The ceremony took place approximately five months after the conventional March graduation window.
Aritomo's Sakura Gakuin membership therefore lasted from May 6, 2016, through August 30, 2020.
Using inclusive calendar counting, that period is 1,578 days.
The delayed graduation did not dissolve the four-person bond professionally.
All four continued together in @onefive.
That continuation is one of the most important facts in Aritomo's career.
Many Sakura Gakuin graduates immediately moved into separate individual paths.
Aritomo's graduating class instead preserved the entire senior quartet inside a new group.
In October 2020, @onefive released “Shizuku.”
In March 2021, the group released “BBB.”
Aritomo also appeared individually in a Nintendo Switch television commercial commonly identified as the “Jibun Jikan” campaign.
The appearance continued the commercial / modeling side of her career while @onefive was still developing its musical identity.
In November 2021, @onefive released “Underground.”
The release was important because the four members became visibly more involved in choreography and visual decisions.
Their Underground documentary material showed the members discussing hair, makeup, costumes, editing, movement and how they wanted the group to appear.
“Just for You” followed in December.
These projects marked an early move away from being only performers who executed finished instructions.
The group increasingly treated its members as contributors to presentation and concept.
On February 2, 2022, @onefive released its first studio album, 1518.
The title connected the group's original “15” idea with the age of eighteen that the members were approaching during 2022.
The members co-wrote the title track and participated in choreography for multiple songs.
For Aritomo, the period also included notable fashion and promotional work with Soyoka Yoshida.
In March 2022, the pair appeared in HOUYHNHNM's “Rojiura Teen” visual feature.
The editorial photographed them at seventeen and emphasized a more natural fashion-documentary atmosphere than a conventional idol costume shoot.
The same period included an appearance in an A-PAB promotional video associated with high-definition satellite broadcasting, titled “Seishun wa itsudatte, kougashitsu eisei housou.”
The work reinforced the long visual partnership between GUMI and SOYO outside concert performance.
From October through December 2022, all four @onefive members appeared in the television drama If My Favorite Pop Idol Made It to the Budokan, I Would Die.
Aritomo played Teramoto Yūka, a member of the fictional Okayama idol group ChamJam.
Yūka is energetic, free-moving and sometimes unable to read the room in the conventional way.
The casting was interesting precisely because Aritomo herself said the character was unlike her natural personality.
She described herself as not originally being the constantly energetic type and enjoyed the challenge of playing someone whose energy moved in the opposite direction.
That comment is useful because it prevents a common mistake in idol-related acting coverage.
A fictional role should not automatically be treated as a direct portrait of the performer's private personality.
The drama's theme song, “Miraizu,” was released on November 6, 2022.
The song marked @onefive's major-label debut through Avex Trax.
On May 12, 2023, the theatrical film adaptation of OshiBudō was released.
Aritomo returned as Teramoto Yūka.
@onefive performed the film theme “Chance.”
The members' ChamJam vocals also appeared on the complete vocal album connected with the production.
The project gave Aritomo a layered professional position.
She was a real former school-idol-group member, a current member of @onefive and an actress portraying a fictional idol inside a story centered on fandom.
The group released the physical single “Chance×Change” on May 24 and “Justice Day” on August 23.
In November 2023, @onefive was appointed Amazon Fashion Japan's Generation Z Leader.
The members modeled seasonal fashion while communicating the perspective of their generation.
Fashion had already been a recurring part of Aritomo's work, so the appointment fit a path visible from child modeling through later editorial projects.
On November 17, 2023, @onefive introduced the @CHIB15 character project.
Each member was represented by an original character.
GUMI's character is ZOEY, a fawn.
In her own comment for the project, Aritomo referred to herself as a self-proclaimed “datsuryoku-kei oneesan,” roughly a relaxed or laid-back big-sister character.
The phrase later became one of the clearest shorthand descriptions used for her within @onefive's public presentation.
It should not be mistaken for an official legal occupation or a claim about her entire private personality.
It is a media-facing character description built from qualities the group and Aritomo choose to emphasize.
On April 17, 2024, @onefive released Classy Crush, its first major-label album and second studio album overall.
The record developed the concept “Japanese Classy Crush.”
“Japanese” emphasized the members' cultural foundation.
“Classy” referred to elegance and inherited convention.
“Crush” represented the desire to break restrictive stereotypes while retaining traditions the members considered meaningful.
The group mounted its first nationwide tour in 2024.
This was an important transition from the pandemic-limited early years into a more conventional live-growth phase.
The four were no longer simply the Sakura Gakuin graduating quartet learning how to continue.
They were establishing a separate performance identity with their own repertoire, fashion language and touring audience.
On August 8, 2024, @onefive appeared in a campaign for the jewelry brand The Kiss.
The campaign used “Love Call,” which later received a digital release in October.
In September 2024, Aritomo's group activity was interrupted.
On September 6, management announced that GUMI would temporarily suspend @onefive activities because she had engaged in conduct described as violating group activity rules.
The announcement did not publish the exact behavior.
Several scheduled appearances during the suspension therefore proceeded with KANO, SOYO and MOMO as a three-member lineup.
This point requires editorial discipline.
The existence of the suspension is documented.
The specific reason is not.
Rumor, social-media speculation and retrospective guesses should not be converted into biography as if management had confirmed them.
On October 1, 2024, @onefive announced GUMI's return to activity after a period of reflection and discussion.
She resumed live group activity later in the month, including the fifth-anniversary period around the 5555 event at Shibuya WWW X.
The interruption was short in calendar terms but significant because it is the clearest formal break in her otherwise continuous @onefive membership.
It did not become a departure from the group.
Aritomo remained GUMI after returning.
On December 31, 2024, @onefive made its first international performance in Tainan, Taiwan.
The event was reported to have drawn an audience exceeding 100,000 people.
The quartet performed material including “Liar Liar” before its official release and presented a cover of Cyndi Wang's “Ai Ni.”
The performance expanded the group's activity beyond Japan and began a period of more regular Asian appearances.
During 2025, @onefive adopted “More Than Kawaii” as a creative theme.
The phrase challenged the idea that “cute” alone could adequately describe young Japanese women or the group's work.
The singles “Liar Liar” and “Kawaii Kaiwai” led into the More Than Kawaii EP, released March 26, 2025.
The members became involved from early stages of song development and co-created ideas and lyrics for “Hanamichi.”
Creative credits should remain collective where the work was collective.
Aritomo was a contributor as one of the four members, not the sole writer unless a specific credit states otherwise.
The More Than Kawaii tour visited Osaka, Nagoya and Tokyo.
International activity expanded throughout the year.
@onefive performed in mainland China for the first time at the TIF Asia Tour in Shanghai in June.
The quartet returned to Taiwan for the Taiwan Comic Exhibition in July and appeared again in Shanghai at @JAM Shanghai Pop Vol. 1.
It later performed at Trendy Taipei J-pop Night at Taipei Arena.
For Aritomo, this international period extended a career that had begun with small-scale childhood modeling into performances before audiences outside Japan.
In October 2025, @onefive released “KIBIDANGO,” a hip-hop reinterpretation of material associated with the traditional Momotarō children's song.
The group also became an ambassador for the game Strinova and recorded the Chinese-language “Miao Miao Xintiao,” based on “Kawaii Kaiwai.”
On November 6, 2025, the weekly FM Yokohama program Urunemu began.
The program extended the members' conversational group identity into regular terrestrial radio.
“Magical Irony” was released on December 17.
On December 31, @onefive performed at the ninth Momoiro Uta Gassen at Nippon Budokan.
That appearance was the quartet's first performance inside Nippon Budokan.
However, it was a multi-artist event.
It did not fulfill the later goal of staging an @onefive headline concert at the venue.
The EP Doh Yoh was released on January 15, 2026.
Its concept reworked familiar Japanese children's-song material through contemporary forms including Afrobeat, hip-hop and hyperpop.
The project continued @onefive's interest in taking culturally familiar material and rebuilding it inside a present-day pop framework.
On February 8, 2026, @onefive formally launched Road to Budokan.
The stated objective is a headline Nippon Budokan performance by spring 2027.
The goal has an additional connection to OshiBudō, whose story is built around the dream of seeing an idol group reach Budokan.
For the four members, that fictional connection now overlaps with a real professional objective.
During 2026, Aritomo's individual television and radio work became more visible.
She appeared live on TOKYO MX's Tamura Atsushi no Kikitai! on April 4 and May 16.
The program centers on discussion of social and public-affairs questions rather than on idol performance alone.
The appearances therefore asked her to listen, react and express a view in a live studio setting.
They should not be described as acting roles.
They belong to her talk / television-personality activity.
On April 1, @onefive launched SAKURAIZATION.
The project explicitly reconnects the quartet's present with their Sakura Gakuin history.
Rather than treating Sakura Gakuin as a closed childhood chapter, @onefive uses musical and conceptual references from that period as material for new work.
“♡Kakumei Shōjo S♡,” released April 15, samples Sakura Gakuin's “Heart no Hoshi.”
“M1X5R,” released May 20, uses the “Oklahoma Mixer” melody also familiar to Sakura Gakuin listeners through “Verishuvi.”
“Muteki☆Atashi Mode prod. ☆Taku Takahashi,” released June 24, samples BABYMETAL's “Doki Doki ☆ Morning.”
The BABYMETAL sample does not make Aritomo a BABYMETAL member or formal BABYMETAL collaborator in the personnel sense.
It is an authorized source element inside an @onefive recording.
The SAKURAIZATION headline concerts were held at EX Theater Roppongi in Tokyo on June 6 and BIGCAT in Osaka on July 3.
The project has particular significance for Aritomo because she spent four years inside Sakura Gakuin and because her final class remained together afterward.
For her, SAKURAIZATION is therefore not an external nostalgia concept applied by a later generation.
It is a reinterpretation of material connected with her own adolescent career.
In a 2026 SAKURAIZATION-period interview, Aritomo discussed the gap between how she can appear publicly and how she has sometimes felt internally.
She noted that people may see her as cheerful or gyaru-like while she has also struggled with complexes and periods of disliking herself.
She described fan support and her identity as @onefive's GUMI as helping her build a more positive relationship with herself.
She also described the group as a place resembling “home,” while acknowledging that the four members are not identical personalities who agree automatically on everything.
That is a more useful description of the quartet's continuity than treating four long-term classmates as if closeness required constant sameness.
In other 2026 interviews, @onefive summarized each member with a short public character phrase.
Aritomo's was “datsuryoku-kei oneesan.”
The phrase emphasizes looseness, calm and an almost deliberately unforced presence.
Soyoka Yoshida has also described that relaxed quality as something that adds an adult or slightly sensual accent to the group.
Aritomo herself has said that she wants to continue polishing that relaxed public quality while also showing the contrast with her cooler stage performance.
She has spoken about wanting more variety work and about challenging herself in singing and collaboration contexts.
She has cited BABYMETAL and Perfume among important goals or examples in discussing the scale of career she wants @onefive to pursue.
The reference is aspirational and professional.
It should not be rewritten as membership, direct mentorship or an announced collaboration unless such a project is separately confirmed.
On June 13, 2026, GUMI appeared with KANO on FM Yokohama's God Bless Saturday.
On July 17, the pair appeared on FM Yokohama's Tresen Friday.
These appearances continued the group's 2026 radio promotion while also giving Aritomo opportunities for live conversational work outside the four-member format.
On August 28, 2026, Aritomo served as a substitute assistant on FM FUJI's Chinmoku no Kinyoubi.
At the August 30 cutoff, this is her latest clearly completed individual radio activity documented in the official @onefive schedule.
The official group schedule also lists @onefive for @JAM EXPO 2026 on August 30.
Because that event falls on the profile cutoff date itself, this profile records the official appearance listing but does not invent set-list details or backstage information that are not independently documented here.
As of August 30, 2026, Tsugumi Aritomo is twenty-one years old.
She turns twenty-two on September 7, 2026.
She remains represented by Amuse and active as GUMI in @onefive.
The group remains a four-member unit: KANO, SOYO, GUMI, and MOMO.
Aritomo's current professional identity is broader than “former Sakura Gakuin member.”
Her career now links child modeling, television acting, Sakura Gakuin, comedy-oriented live talk, @onefive music, fashion, fictional idol acting, international performance and adult television / radio conversation.
