一人息子の担任である年下教諭と懇親会で親しくなり、相談と称し度々二人きりで話す関係になったひかり。やがてカラオケ店で密会するようになり肉体関係に発展。最初は理性を保っていた男もひかりの包容力と積極的なアプローチに耐えられず不倫セックスに没頭していく

Hikari became close to her younger son's teacher at a social gathering, and under the guise of seeking advice, they began to talk alone frequently. Eventually, they started meeting secretly at karaoke bars, and their relationship escalated to a physical one. At first, the man maintained his composure, but he could not resist Hikari's warmth and assertive approach, and he became engrossed in their adulterous sex.