Kai is a minor character in Beastars and a student at Cherryton Academy. He is a mongoose, identifiable by his small stature, slender build, and brown fur. His most distinctive background detail is that he was abandoned by his biological parents as a newborn and was subsequently adopted and raised by a family of hyenas. This experience of being a small carnivore raised among larger, different ones may inform his determined and sometimes aggressive personality.

Initially, Kai is a member of the drama club's acting troupe. He is introduced as being eager, brash, and intensely driven to prove himself, to the point of selfishness. Following the death of the alpaca Tem, Kai shows little sorrow, instead viewing the tragedy as a personal opportunity for advancement, believing he would naturally inherit Tem's lead role. When it is announced that another student, Zoe, has been chosen instead, Kai impulsively storms into Louis's office to demand an explanation. Louis reprimands him for previous onstage mistakes and informs him that he is being demoted from the acting team to the stage crew. Enraged by this, Kai moves to strike Louis, but the larger wolf Legoshi intervenes. When Kai then tries to threaten Legoshi, he immediately backs down upon seeing the wolf bare his fangs, revealing that his aggression may be more defensive bluster than genuine threat.

Though his ego is initially bruised by the demotion, Kai undergoes a notable shift in his role and personality. He begins working on the stage crew, specifically in costume and design, where his talents are recognized and praised by fellow student Dom. As he finds he fits in well as a stagehand, his aggressive demeanor mellows considerably. He develops genuine friendships and discovers the appeal of backstage work. His primary relationships are therefore shaped by this transition; he is in conflict with the powerful Louis, who demoted him, and is protected by Legoshi, whom he later shows genuine concern for after the incident with the Shishigumi crime syndicate. This demonstrates that while still self-centered, he possesses a deeper capacity for empathy beneath his fiery surface.

In terms of abilities, while he fails as a stage actor, Kai proves to have a good sense of design and technical aptitude. He becomes a capable member of the stage crew, ultimately serving as a lighting technician. His storyline explores themes of ambition, disappointment, and finding one's place, as he learns to adapt to a supporting role where his new skills are valued. Though he remains a minor character, his arc provides a perspective on the hierarchy within the drama club and the ways students deal with failure and redefine their own worth.