Naoaki, the nephew who has been staying at his affectionate and trusted aunt Eriko's house since childhood, gradually begins to see her as a woman without even realizing it himself, causing him to act awkwardly around her. Eriko notices Naoaki's subtle changes and, drawn by her own growing affection, continues to treat him gently and warmly. One day, when Eriko enters his room and moves close to him, Naoaki becomes tense and aroused, his crotch swelling involuntarily. Sensing his reaction immediately, Eriko smiles and draws her body nearer, deliberately pressing against his groin. The story unfolds naturally as their relationship takes an intimate turn.