Katai has black hair and wears small circular glasses and is often found resting in his futon within the comfort of his home. His attire consists of a white button-up shirt, a patterned robe over his shoulders, and dark pants.
He is an anxious, nervous, easily stressed out and unmotivated man, who lies in his futon all day, refusing to go outside or communicate with others. Because of this, Kunikida described him as a hikikomori for reclusively shutting himself at home for extended periods of time, isolating himself from society.
His ability, Futon (蒲団 Futon?), allows him to control any electronics within sight as long as he isn’t touching them. His ability also enables him to process information dozens of times faster than an average human.
Additionally, it seems that Katai can only concentrate wherever his body and mind are most relaxed. Although Kunikida mentioned that he can only activate his ability when he’s wrapped in his futon, Katai has shown to be able to use his ability and change the signal of a pedestrian traffic light even without it.
Katai and Kunikida first met each other 10 years ago. According to Kunikida, when Katai was dragged out of his room to join the Agency, he laid out a futon in his office and began living there and even locked himself in his room to avoid going out.
- His friendship with Kunikida mirrors the real Katai Tayama's friendship with Doppo Kunikida after joining the Literary World (文学界, Bungakukai?) group.
- Bungo Stray Dogs Manga: Volume 15.