Rina Izutsu works as a clerk alongside Junpei Takamori at his rural job posting. She has long light-colored hair and a whimsical, fun personality that makes her popular with male colleagues. Her initial contact with Junpei involves seemingly trivial text messages about the weather or health. She rationalizes getting his number as necessary for emergency crew contact and shows visible happiness upon reconnecting. Rina actively pursues Junpei romantically, having first met him on a dating app before becoming his coworker. She invites him to her home while her husband is away, leading to physical intimacy. Her husband, Wataru Izutsu, discovers the affair during one visit. Rina believes Junpei is her destined partner and uses whispered expressions of affection and wishes for marriage to secure his commitment.

Rina's background involves financial constraints leaving her a high school graduate, fostering inferiority towards her husband, Wataru. He holds a degree from an elite university, works as a consultant at a foreign accounting firm, and comes from a wealthy Minato ward family in Tokyo. Rina feels suffocated in the marriage by Wataru's controlling, chauvinistic, and possessive behavior, where he treats her as property. This causes unhappiness and feelings of insignificance. Despite dissatisfaction, she lacks the confidence or capability for independence, compelling her to endure the marriage while seeking emotional escape through the affair.

After the affair is exposed, Rina refuses to let go of Junpei. She intensifies efforts to sabotage his attempts at reconciling with his wife, Azu, engineering situations to fracture their trust and make Azu appear unfaithful. Rina leverages Junpei's lingering guilt and reluctance to set boundaries, maintaining contact and doing him favors to sustain his emotional obligation. Her persistence escalates into profound obsession and stalking. She stages a public confrontation at Junpei's company, culminating in a dramatic performance to publicly shame him and endanger his livelihood.

Rina's relationship with Wataru deteriorates further post-discovery; he responds with violent abuse and relentless criticism of her infidelity. After their separation, he assumes greater responsibility for their children while Rina faces exclusion from the family. Her narrative concludes with extreme actions driven by her fixation on Junpei and inability to accept rejection, marking a progression from marital dissatisfaction to destructive obsession.