Kosuke, the son, finds himself captivated by Sumire, his mother's friend, enchanted by her refined and elegant beauty. Overcome with nervousness, he missteps in conversation, takes a joke too seriously, and unexpectedly shares a passionate kiss with her. That night, Sumire's heart races from the young man's kiss, left too aroused to sleep. At dawn, Kosuke returns to her room. Though they promise each other it will only happen tonight, they give in and make love. But Kosuke's passion doesn't end there. The next day, he sneaks into Sumire's room again, confessing deeper feelings. Their forbidden relationship deepens in a story woven with longing and temptation.