Kana Arima — Oshi no Ko

Biography

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Oshi no Ko

Kana Arima有馬かな

Former child actress, aspiring leading actress, and member of the revived idol group B-Komachi

Kana Arima is an actress and idol in Aka Akasaka and Mengo Yokoyari’s Oshi no Ko. Famous as a child performer who could cry on cue in ten seconds, she grows up to find that early celebrity no longer guarantees acting work. Reuniting with Aqua and Ruby Hoshino brings both a chance to reclaim her craft and an unexpected invitation to join the revived B-Komachi, where her singing earns her the center position.

Quick with a cutting remark but exacting about her work, Kana wants to be judged as the actress she is now rather than the child star people remember.

Biography

A child actress whose fame came early

Kana works in entertainment from early childhood and becomes known as a “genius child actress” who can cry in ten seconds. Her precocious confidence makes her difficult to work with at times, while a childhood encounter with Aqua Hoshino challenges her assumption that being the most celebrated young performer means being the best actor in the room.

A career that refuses to disappear

As Kana grows older, her childhood celebrity fades. Rather than abandon acting, she learns to adjust her performances to the needs of productions and less experienced costars, sometimes holding back what she can do. By the time she meets Aqua and Ruby again at Yoto High School’s entertainment program, she remains committed to performing even though her career is no longer secure.

The Sweet Today turning point

Kana stars in the live-action adaptation of the manga Sweet Today, where uneven acting around her has lowered expectations for the production. When Aqua joins for the final episode, their shared scene gives her room to act with the intensity she has been suppressing. The experience renews her confidence in her craft and changes the way she sees him.

A reluctant idol and an unlikely center

Ruby and Aqua recruit Kana into the new B-Komachi. She initially resists because an idol career could complicate her ambitions as an actress, but eventually accepts. Ruby and MEMcho choose her as the group’s center in recognition of her singing ability. Although Kana worries that she will fade beside the others, she steps onto the stage and gradually discovers what performing directly for an audience can mean to her.

Returning to the stage with Tokyo Blade

Kana plays Tsurugi in the 2.5-dimensional stage adaptation Tokyo Blade, sharing the production with Aqua and fellow actress Akane Kurokawa. The ambitious theatrical staging brings the actors’ different methods into focus. Kana’s habit of supporting her castmates must coexist with the chance to command attention through her own performance.

Personality and Motivations

Kana is frank, competitive and quick to defend her judgment. She can sound dismissive or prickly, especially when embarrassed, yet her bluntness coexists with a careful understanding of how performances are assembled and how much a production depends on its weakest parts.

Her self-assurance is often conditional. Losing the easy status of a famous child star makes her sensitive to being passed over or treated as replaceable; she compensates by preparing thoroughly and by becoming unusually skilled at fitting her work around other actors. The resulting tension—wanting recognition while making space for others—is central to her early development.

Kana is capable of affection and loyalty without being graceful about expressing either. She teases people whose opinions matter to her, measures herself against performers who seem to draw attention more easily, and still returns to the demanding work of rehearsal rather than assuming recognition should come automatically.

Appearance

Kana is petite, with a short, straight red bob and bangs, large reddish-pink eyes, and an expressive face. Her official anime character designs frequently pair her with a dark beret and a Yoto High School uniform featuring a navy jacket and prominent pink bow.

Her wardrobe changes between school, acting jobs and B-Komachi performances. Official character materials distinguish her stage-play costume from her idol outfit, so neither should be mistaken for an outfit she wears in every appearance.

Quick facts

Japanese name: 有馬かな
Height: 150 cm (official promotional character profile)
School: Yoto High School, entertainment course (at her introduction)
Professional background: Child actress who continues acting as a teenager
Idol group: Revived B-Komachi (alongside Ruby and MEMcho)
Group position: Center vocalist
Stage role: Tsurugi in Tokyo Blade
Glow-stick color: White
Japanese anime voice: Megumi Han

Abilities

Emotional acting

Her child-star reputation rests on being able to cry on cue in ten seconds; later work emphasizes her control of expression and emotional timing.

Ensemble-aware performance

Kana can adjust the force of her acting to suit a scene, accommodate less capable costars and preserve the overall production.

Limitations: Holding back too often can keep her strongest work from being seen.

Live stage acting

Her performance as Tsurugi in Tokyo Blade shows that she can work within an ambitious theatrical ensemble while bringing her own dramatic presence to the stage.

Singing and idol performance

Kana’s singing helps earn her the center position in the revived B-Komachi, where she also undertakes rehearsal and live performance.

Limitations: Her early insecurity about idol work and habit of comparing herself with her fellow members make it difficult for her to enjoy the spotlight.

Relationships

Aqua Hoshino

Childhood costar, later acting colleague and personal interest

Kana knew Aqua as a child and reunites with him in high school. Their collaboration on Sweet Today becomes an important early turning point, and his opinion carries unusual weight for her.

Ruby Hoshino

Fellow B-Komachi member and friend

Ruby helps draw Kana into B-Komachi. Their different strengths make Kana alternately protective of and competitive with her fellow idol.

MEMcho

Fellow B-Komachi member

MEMcho performs with Kana and Ruby in the revived B-Komachi. Her experience attracting and engaging an audience contrasts with Kana’s longstanding focus on acting.

Akane Kurokawa

Professional rival and fellow actress

Akane once admired Kana as a child actress. Their history produces friction, and their different acting approaches come into sharp relief when both join the Tokyo Blade production.

Interesting facts

The nickname “Baking Soda-chan” grew from Ruby’s mangled recollection of Kana’s famous ability to cry in ten seconds.

The joke contrasts Kana’s carefully maintained child-star image with how little control she has over the way other people remember her.

As a child entertainer, Kana performed the novelty song “Bell Pepper Exercise,” despite disliking bell peppers herself.

A food she dislikes became part of her public child-star image, even though she later wanted to be taken seriously for her acting.

Kana’s official promotional talent page includes a collaboration with a real baking-soda brand using her nickname.

The production deliberately carried a fictional misunderstanding into an outside-the-story promotion; it is not a claim that the collaboration happened inside the manga.

Frequently asked questions

Who is Kana Arima in Oshi no Ko?

She is a former child acting prodigy who continues working as an actress and becomes a member of the revived idol group B-Komachi.

Why is Kana called Baking Soda-chan?

Ruby mangles the phrase describing Kana as a child actress who can cry in ten seconds, producing an accidental baking-soda nickname that follows Kana afterward.

Is Kana an actress or an idol?

Both. Acting is her longstanding career, while the revived B-Komachi gives her an additional role as an idol and singer.

What role does Kana play in Tokyo Blade?

She plays Tsurugi in the stage adaptation.

What is Kana’s B-Komachi member color?

White. It is the color associated with her glow sticks during group performances.

Who voices Kana Arima in the Japanese anime?

Megumi Han voices Kana in the Japanese-language anime adaptation.

Major story spoilers below.

A scandal that exposes a different secret

While struggling to secure acting work, Kana meets film director Masanori Shima at a gathering and is photographed entering his apartment. Although the feared affair does not take place, the images threaten a damaging tabloid story. Aqua averts publication by negotiating a different, sensational disclosure: that Ai Hoshino secretly gave birth to Aqua and Ruby. The information protects Kana from the immediate report but creates profound consequences for Ruby and her family.

Playing Nino, confronting Ruby

In the film The 15-Year Lie, Kana is cast as Nino, a former member of Ai’s original B-Komachi; Ruby plays Ai. Kana’s understanding of envy and resentment helps her approach the role. When Ruby struggles to grasp the emotional tensions around Ai, Kana openly confronts her with jealousy she has felt herself. The confrontation damages their easy friendship for a time but also gives their difficult on-camera exchanges greater honesty.

Choosing an acting future

Kana decides to graduate from B-Komachi and concentrate on acting. After filming The 15-Year Lie, she invites Aqua back to their old school, where they play catch in their school uniforms. She tells him that becoming the person he supports most—his favorite idol—has become a personal dream, and asks him to attend her Christmas graduation concert. Their closeness is unmistakable, but the scene does not establish that they become a couple.

The graduation concert without Aqua

B-Komachi’s Christmas tour finale becomes Kana’s farewell performance as an idol. She performs with Ruby and MEMcho, but Aqua is not in the audience to see her final concert, despite her invitation. While the group is onstage, he is occupied with the confrontation with Hikaru Kamiki that will end his life. The absence leaves Kana’s hope of being the person Aqua comes to watch unfulfilled.

The farewell Kana never expected

Aqua dies after confronting Hikaru Kamiki. Kana is devastated, especially after his absence from her farewell concert. At his funeral she slaps his face, fulfilling an earlier promise to do exactly that if he ever died; Miyako slaps Kana in response. Kana then breaks down over the love she can no longer tell him about. The action, while shocking, follows a prior exchange between them rather than an unrelated outburst.

What the completed manga establishes

Kana survives the completed manga and pursues acting after leaving B-Komachi. The final chapter depicts the people closest to Aqua continuing their lives and work in the aftermath of his death. The extra pages in collected volume 16 take the story further: reports within the epilogue show Kana becoming a successful actress whose career reaches Hollywood. Her relationship with Aqua never becomes an established romance, and the story does not suggest that professional success cancels her grief.

Additional story facts

Collected volume 16 contains an additional epilogue not present in the initial weekly-series ending.

Kana’s later acting success is documented in this added material, rather than by treating chapter 166 alone as a complete account of her future.

Shueisha also published the separate prose novel Two Etudes, centered on Kana and Akane rehearsing for a joint lead stage production after The 15-Year Lie.

It offers additional officially published material about their working relationship but should be identified as a prose spinoff, not misrepresented as a scene from the original manga.

An early flash-forward interview has Kana refer to an “A-kun”; the manga later makes clear that this is her familiar way of referring to Aqua.

An apparently casual line near the beginning gains new context as Kana and Aqua’s connection develops.