Hiroshi, an only child, finds his life turned upside down when his father remarries a woman twenty years his junior, bringing stepmother Azumi into his home. Unemployed and with little experience around women, Hiroshi is instantly drawn to Azumi's youthful, tight body—his first real temptation. Aware of his innocent feelings, Azumi deliberately teases him, pushing him to the edge again and again. Just when he thinks their teasing game will continue indefinitely, a major shift occurs in their relationship.