Jun Watanabe is 24 years old and lives in Kanagawa Prefecture, balancing life as a housewife and part-time worker. Confident that her breasts are unmatched by anyone else's, she decides to cheat on her husband as revenge for his infidelity—marking her first time being unfaithful. Initially not expecting to feel any pleasure at all, she unexpectedly finds herself caught in an intense session of sadistic S-play, unable to hold back her moans. Drawn into the experience by her innate masochistic tendencies, she gradually becomes deeply immersed, dazed and tearful as she whispers, "I've never felt anything this good before..." In the end, she reaches a dramatic climax, completely drained and utterly exhausted.