The story begins with Tojo Aoi, a high school student, embarking on a new chapter of his life by moving into his own apartment. Still grappling with the aftermath of a "promised goodbye" with his first love from middle school, Aoi attempts to establish a new routine, including daily strength training, as a way to cope and move forward.
On his moving day, while Aoi is mid-workout, his peace is abruptly shattered when a girl casually enters his unlocked apartment. This intruder is Fujisaki Utaha, his new next-door neighbor, characterized by her distinctive white hair and a teasing, sarcastic demeanor. Utaha immediately begins to provoke Aoi, commenting on his sweat and implying his intense training is a desperate attempt to distract himself from heartbreak, even suggesting he was "netorare" (cheated on or stolen from). Aoi vehemently denies this, insisting his breakup was "inevitable" and his training a long-held personal goal, but Utaha dismisses his protests with knowing smirks, further frustrating him.
Their initial interaction is a clash of personalities: Aoi is earnest, easily flustered, and defensive about his past, while Utaha is sharp-witted, confident, and seems to delight in his discomfort. As she prepares to leave, feigning disgust at his smell and promising to buy Febreze, Utaha delivers a shocking revelation. Turning back at the door, she smirks and casually states, "...even though you lost your virginity to me." This unexpected confession completely disarms Aoi, causing him to collapse in shock, confirming the truth of her words and revealing a deep, intimate, and previously secret history between the two.
This encounter transforms their relationship from that of new neighbors to individuals bound by a shared, hidden past. The chapter arc shifts dramatically from Aoi's attempt at a fresh start and emotional recovery to the immediate and unavoidable re-entry of a significant figure from his past, who holds a powerful secret over him. The initial conflict of Aoi trying to deny his heartbreak evolves into a more complex dynamic, where his personal boundaries and secrets are immediately exposed by the very person he now lives next to.
