Goro, a high school student, wins a "trip to Hawaii" in a neighborhood lottery to give to his mother, Chisato, but when he sees his mother back home, he can't help but cry out. Her whole body is tanned, and the sensual marks of her swimsuit are clearly visible. Goro can't stop fantasizing about his mother's lewd tan lines while she is cleaning or doing the laundry, and he desperately tries to suppress his desire, but he is at the mercy of his mother's sweet words: "Mom, I'm so hot, I'm flushing, I'm going crazy..."