Despite being a key member of the department, office lady Mami gives off a somewhat plain vibe. Although she has a boyfriend, the flashy and attention-seeking guy at work, Hirai, carelessly starts pursuing her. Eventually, he succeeds in luring her to his place and persuades her into having sex. Yet Mami, holding onto pride as someone's girlfriend, secretly harbors her own desires even as she responds to his advances. Seeing this, Hirai taunts her with a smirk, "You've never done this for your girlfriend either, right...?" treating the whole thing like a game. He leers at her body, indulging himself as they passionately entwine their mucous membranes together, lost in overwhelming pleasure—completely unable to break free from this intoxicating sex.