A lonely Japanese stepmother, yearning for connection, finds an unexpected outlet with her teenage son. She begins helping him with his "personal needs," guiding him through the complexities of masturbation. As they grow closer, their dynamic shifts, and soon, she's not just instructing, but joining in. Her soft, experienced hands replace his clumsy teenage fumbling, bringing him to heights he's never known. But as their bond deepens, so does the taboo, threatening to consume them both.