Tsubasa was in love with his childhood friend's mother, Yui. One day, when he got his family register to get a passport, it said that Yui was his birth mother. Knowing that this day would come someday, Yui and his adoptive parents tell the truth. Yui and Tsubasa go on a trip to a hot spring to talk it over. He never imagined that the woman next door was his real mother and the person he loved... Tsubasa kisses his mother and caresses her big breasts. Freed from reason, the two indulge in the act of love on this forbidden hot spring trip.