An adulterous sex movie of Nao Jinguuji and her husband who have been married for several years. Her husband became increasingly cold and less interested in her than when they were newly married. Nao feels extremely lonely as her husband seems to grow further and further away from her. Her husband’s birthday is coming up, and Nao wants to use this opportunity to make the relationship between husband and wife better. Wanting to look her best that day, Nao went to the swimming class on the flyer. Nao is gradually attracted to the kindness and concern of her handsome swimming coach. When her husband always shunned her, he didn’t even come to the birthday dinner she gave him. Frustrated, Nao turns to her swimming coach, the only one who can warm her heart right now…