Katai Tayama is a reclusive figure with unkempt black hair, pale eyes obscured by round glasses, and a scruffy beard, typically clad in a patterned robe draped over a plain white shirt and dark trousers. He is rarely seen without his tattered futon, affectionately dubbed Yoshiko—a nod to a character from his namesake novel *Futon*. His severe anxiety and aversion to social interaction solidify Kunikida’s labeling of him as a hikikomori, yet he shares a steadfast, decade-long bond with Kunikida, who brought him into the Armed Detective Agency. Katai’s ability, *Futon*, grants him unparalleled control over electronic signals and devices within his visual range, executing tasks at superhuman speeds. Though Kunikida insists the power hinges on his being swathed in the futon, Katai defies this during crises—diverting traffic to shield Gin—implying psychological barriers rather than physical constraints. The ability’s potency matches elite cyber warfare units, allowing rapid breaches of secure systems. A former corporate white-hat hacker, Katai joined the Agency and retreated into office life, enduring a week-long confinement by surviving on delivered meals. His isolation contrasts sporadic acts of initiative: aiding Kunikida in tracking a stalker, reconstructing the Moby Dick’s navigation post-Guild conflict, or mustering courage to confess feelings for Gin after the Guild’s downfall. Her rejection, rooted in Port Mafia loyalties, halts his brief social defiance. During the Cannibalism arc, Fyodor Dostoevsky ambushes Katai while probing the House of the Dead, though Sōseki Natsume ensures his survival. Later, he pinpoints the Rats’ hideout and, when the Agency is framed, evades capture via a smartphone linked to Edgar Allan Poe’s ability, fleeing into a novel-world sanctuary. His strained interactions—like addressing Akutagawa as “Ani-ue-dono” despite open disdain—underscore clumsy yet earnest efforts to connect. Katai’s evolution reveals fleeting shifts toward engagement, spurred by loyalty to the Agency or personal sparks like his crush on Gin. Yet his foundational traits—crippling anxiety, reliance on Yoshiko—persist, anchoring him even as external pressures nudge him beyond his self-imposed solitude.