Rin's husband is working away from home, and her son has accompanied him, so she is enjoying the feeling of being single and living alone. One day, she finds out that Takuto, the son of a mommy friend, is a part-time co-worker. Rin, who is frustrated by her sexless life, is intrigued by his strong body and sneaks out for a drink alone... Since then, the two, who are only part-timers, have been enjoying an affair, repeating thrilling and exciting infidelity wherever they are during work hours, drowning in pleasure. And every time she punches out, her body naturally starts to ache...