"What would have happened to us if we hadn't broken up then?" Yu (Yuu Kawakami), who met her ex-boyfriend Atsushi at a class reunion, blurted out the feelings she had been hiding deep in Kokoro in the heat of her drunken state. Now that they both have families, Yu knew she shouldn't say it, but the moment she saw Atsushi's face for the first time in 20 years, the intense emotions of her teenage years were brought back to life. Then, her husband was sent on a business trip and would be away from home for three days. She might never get another chance to be alone with Atsushi. Yuu could no longer contain her feelings...