Married for 25 years, Chisato's daughter is now an adult and she lives an ordinary but happy life. She has a good relationship with her husband and isn't particularly dissatisfied. It was at this time that Chisato meets Matsuki, a university student who attends the same university as her daughter. At first, their relationship was nothing special. However, Matsuki fell in love with Chisato at first sight. Matsuki knew that their relationship was forbidden, but he was a pure and modest young man. Seeing Matsuki's honesty reminded Chisato of her youth. "I'm seriously in love with you, Chisato-san..." "What are you talking about already?" "I know that sounds strange. Chisato-san has a husband and China-chan, so... I know that it's an unrequited love..." "...Matsuki-kun..." "Finally...can I hold your hand?" "Huh?... What should I do..." "With this... I'll give up..." Chisato instinctively holds his hand. At that moment, the Kokoro that had been sleeping inside Chisato is awakened. A love that she had forgotten for years... Those feelings destroy her reason and develop into a forbidden relationship.