Natsumi Tachibana (Hikaru Takahashi) died in the spring of 2009 when she was 10 years old with her mother, Kyoko (Naoki Kondo). At that time, Natsumi despises her father, Koji (Kisuke Iida), who makes the shadow of a woman flicker, and decides to live with her younger sister, Haru (Hiyori Sakurada), as the only family. However, in the winter of 2019, there is a danger that the bond with his sister will be shaken by the matchmaking with Fuyugo Hiiragi (Asuka Kudoh) who came to his sister. Fuyugo is the third son of the Hiiragiya, a branch of the Soma conglomerate, who is a distant relative. It was spring when Fuyugo's mother, Seimi (Reiko Takashima), noticed.