Katai has short black hair and wears small, circular glasses that give him a scholarly appearance. He is often seen lounging in his futon, emphasizing his preference for a reclusive and comfortable lifestyle. His usual attire includes a white button-up shirt paired with a patterned robe draped over his shoulders, complementing his dark pants. This casual and somewhat unkempt appearance reflects his laid-back personality and preference for staying indoors

Katai is an anxious, nervous, and easily stressed individual who lacks motivation and prefers a life of solitude. He spends most of his time lying in his futon, avoiding the outside world and social interactions. This behavior has led to Doppo Kunikida referring to him as a “hikikomori,” a term used to describe individuals who isolate themselves at home for prolonged periods. His reclusive tendencies highlight his discomfort with societal norms and his desire for a stress-free, solitary lifestyle.

Katai’s ability, Futon (蒲団, Futon), grants him control over electrical signals, allowing him to manipulate and interact with any electronic devices within his line of sight. This ability also significantly enhances his mental processing speed, enabling him to analyze and process information at a rate far surpassing that of an average human.

While it is commonly believed that Katai can only fully concentrate and activate his ability when he is wrapped in his futon his place of comfort he has demonstrated the capability to utilize it even without being in this state. For instance, he has been shown altering the signal of a pedestrian traffic light without the use of his futon, indicating a degree of flexibility in his ability’s activation. Despite this, his optimal performance seems to align with his relaxed and familiar environment.

Katai first crossed paths with Kunikida a decade ago. Their initial connection deepened when Katai was recruited to join the Armed Detective Agency. However, his reclusive tendencies immediately became evident, as he reportedly brought a futon to the office and essentially began living there. True to his nature, Katai often avoided leaving his workspace, sometimes locking himself in his room to avoid venturing outside. This behavior solidified his reputation as a hikikomori within the Agency, and his reluctance to engage with the outside world became a defining aspect of his time there.

Katai’s role as an information broker allows him to gather and analyze data for the Armed Detective Agency, often uncovering critical leads in their investigations. His ability to operate from a distance ensures that he can assist the agency even in high-risk situations.

Katai’s interactions with former colleagues, particularly Osamu Dazai, often provide humorous moments that lighten the tone of the series. Despite his comedic role, Katai’s contributions are vital, showcasing his loyalty and resourcefulness.

In moments of danger, Katai proves himself to be a dependable ally, using his ability and technical skills to support the agency. His unique perspective and unconventional methods often lead to innovative solutions.

Katai Tayama’s character in Bungo Stray Dogs highlights themes of loyalty, resourcefulness, and the value of intellect over physical presence. His unique ability, combined with his eccentric personality, makes him a memorable and indispensable ally to the Armed Detective Agency. Despite his humorous quirks, Katai’s contributions to the agency’s success underscore his intelligence and unwavering dedication to justice.