Hisashi Seki, an unremarkable salaryman at a Shinjuku auto parts firm, endures a monotonous routine of clocking nine-to-five hours, commuting by motorcycle, and returning to his solitary apartment. This predictability fractures when he finds a naked woman, Asami, in his bed—a self-proclaimed “ideal partner” wielding unexplained telekinesis and interdimensional abilities. Ignoring the mystery of her origins, he embraces her presence, captivated by her allure.

His past holds no traces of the supernatural, anchored solely in the mundane rhythms of corporate life. Asami’s arrival spirals his world into chaos: hallucinatory visions of her trigger a motorcycle crash, followed by a reckless police chase. Despite her volatile quirks—failed culinary attempts, alcohol-induced power surges sparking indoor hailstorms—Hisashi’s attachment deepens, prioritizing her companionship over rationality.

Their bond strains further when interdimensional rules intervene. Asami hails from a mirror universe where manufactured soulmates are forbidden from merging with humans. Hisashi battles doppelgangers, including a lethal nude counterpart wielding a knife, surviving through pragmatic improvisation. His resolve stems less from heroism than a craving for connection.

Forced fusion—a merging of their bodies into a single hermaphroditic form—becomes a mandated compromise. This union, dissolving nightly and rekindling through intimacy, perpetuates an unstable equilibrium. Their relationship oscillates between cohesion and fragmentation, adapting without permanence.

External tensions escalate via Sugiyama, Hisashi’s boss, whose relentless romantic pursuits only cease after a mirror-universe confrontation. Hisashi deflects these advances with passive evasion, contrasting his tenacious efforts to stabilize life with Asami. The saga concludes without expansion, leaving their cyclical existence unresolved.