Ritsurou Yoshinari is a diligent high school sophomore balancing conventional student life with familial responsibilities, residing with his mother and middle school-aged sister Nami. Defying Japanese labor restrictions for teenagers, he concurrently works part-time as a convenience store clerk and an Italian restaurant waiter, showcasing his strong sense of duty.

His longstanding bond with troubled best friend Ken Amafuji originates in middle school, though Ritsurou initially grapples with Ken’s self-destructive tendencies. When Ken drops out of high school after his parents’ divorce, Ritsurou moves into Ken’s apartment to provide stability, unintentionally positioning himself at the epicenter of escalating turmoil. This intensifies after Ken deliberately sleeps with Ritsurou’s longtime girlfriend Moeko Kohashi to sabotage their relationship and convey his own unresolved emotions.

Throughout their cohabitation, Ritsurou wrestles with profound confusion over Ken’s actions, including Ken’s history of undermining his romantic pursuits. His inability to consummate his relationship with Moeko becomes a critical indicator of subconscious conflict. Discovering Ken’s entanglement with Moeko triggers a confrontation, leading Ritsurou to temporarily return home.

A pivotal shift occurs upon learning of Ken’s imminent relocation to Singapore. This revelation sparks clarity, driving Ritsurou back to Ken’s apartment where he openly confesses reciprocal romantic feelings. Their ensuing physical relationship marks his acceptance of this transformed dynamic.

Ritsurou then navigates the fallout, including Moeko’s visceral distress upon witnessing his intimacy with Ken. Her subsequent decision to cut her hair short mirrors the emotional upheaval caused by his transition from a conventional partnership with her to a committed relationship with Ken.