Sanpeita is a male character defined by his obsessive pursuit of photographing a specific female character’s undergarments, relentlessly stalking her while concealing himself in a vaulting box to avoid detection. His fixation remains singular, targeting only the protagonist with no interest in others, even in comparable scenarios. His antics generate darkly comedic tension, often escalating into exaggerated schemes—such as collaborating with a friend who manipulates a fan to expose the protagonist’s underwear—to achieve his narrowly focused goal. Despite recurring appearances, his role remains static, devoid of personal history, relational depth, or evolution across official narratives, existing solely to perpetuate his single-minded, unsettling pursuits.