Shūsuke Takanashi, heir to the Takanashi household, balances a flagrantly lecherous persona—hoarding explicit magazines and chasing voyeuristic thrills—with an unspoken devotion to his adopted sister Nao. Though he masks his feelings under the guise of sibling loyalty, his restraint stems from a buried guilt: Nao’s adoption followed her parents’ fatal accident, a tragedy he helped orchestrate, and her non-biological status fuels his internal battle between desire and protectiveness.

His childhood exploits with Iroha Tsuchiura, including “doctor” games to glimpse her naked, warped her perception of their bond, cementing her delusion of being his fated lover. Shūsuke deflects her relentless pursuit, haunted by his role in shaping her obsession. Similarly, class president Mayuka Kondō entraps him in a cycle of purchasing and critiquing Boys’ Love content after he ruins her prized magazine, forcing him into traumatic exposure to homoerotic narratives and nightmares involving friend Keiichirō Kishikawa.

Aligned with the A.G.E. Explorers—a club trading illicit media—Shūsuke’s antics clash with fleeting urges for normalcy, particularly in preserving his fractured yet earnest relationship with Nao. His father, Shūji, mirrors his vulgar proclivities, while mother Nanaka coldly labels him a born degenerate.

Chaos follows Shūsuke through overlapping affections from Nao, Iroha, and Mayuka, as well as absurd trials like cosplay rituals with sisters Ran and Rin Yatagai. Blackmail, stalking, and compromising scenarios punctuate his life, occasionally sparking introspection—brief vows to reform after recognizing his harm to others, though peer pressure swiftly unravels such resolve.

Beneath the raucous humor lies unresolved guilt over Nao’s past and a fractured self-image torn between carnality and brotherly duty. Each action ripples into unintended consequences, shaping his turbulent growth as he navigates desire, responsibility, and the ghosts of choices made long ago.