Shinnosuke Tenmaya, a Japanese-American teenager, manages a clandestine specialty store catering to vampires, offering essentials like synthetic sustenance and forged identity documents. Inheriting the establishment from its late proprietor, he maintains its legacy as a discreet refuge for unregistered vampires seeking resources without exposing their existence. His mixed heritage once made him a target for bullying, driving him to dye his naturally violet-tinted hair black in an effort to blend in.

Orphaned early in life, he lives with his uncle and cultivates a guarded personality, speaking sparingly unless clients encounter danger. His striking appearance features a deep-purple kimono paired with a turquoise obi, traditional wooden sandals, and an enigmatic monocle, while a small arrangement of feathers woven into his hair underscores his unconventional aesthetic.

The shop operates under his pragmatic philosophy of aiding vampire survival through calculated support, balancing accessibility with vigilance. His efforts focus on supplying necessities and covert aid to ensure his clients navigate human society undetected, steadfastly guarding their secrets as rigorously as his own.