One day, Ezawa Jun, who has trouble with work and in love, gets a ryukin from a goldfish scooping game at a festival. However, she is actually a beautiful girl and she suddenly turns into a human form and appears in front of Jun. Called Ryu, she is looking for the legendary black ranchu and asks Jun for his help. The two strangers begin living together and growing closer. Their fate goes in an unexpected direction.
Asuka Goda is a 40-year-old pastry chef who runs a sweets store. She works with pastry chef Seiya Hanada, who is younger than her, and Kenichi Gonda, who wants to become a pastry chef. One day, Seiya Hanada confesses to Asuka Goda about his feelings for her. Her situation brings back bad memories to what happened 5 years earlier. At that time, Asuka Goda was in an affair with store owner Junji Awai and also in a relationship with gym trainer Shunsuke Nomura. Asuka Goda decides to go to mysterious "Clinic Love Doc." The clinic lets people know everything about love with a gene test.