High school student Shinichi Kudo (Junpei Mizobata) and childhood friend Ran Mouri (Shiori Kutsuna) are private detectives.
Right after they leave a nail salon on the first floor of a mansion they hear a man screaming. When Shinichi and Ran arrive there, cameraman Yuhei Tsubouchi (Akira) and an assistant lie on the ground bleeding. The owner of the house and model Momoko Aida are dead.
The investigation begins. The cameraman's assistant testifies that he was by an iron-bar by a man who came from another room. Yuhei, who is Momoko's brother-in-law, asks the detectives to catch the criminal. A puzzling aspect about the case is that the criminal used an iron-bar, but the model was strangled to death. Can Shinichi uncover the truth?
Humanity has always been obsessed with the idea of somehow regaining our youth and going back to our childhood. But what would happen if that dream became a reality? Would that really bring happiness… or tragedy?
Yuko has a promising career in journalism ahead of her, and is happily married to Satoru, a younger man. But an unfortunate event turns their world upside down, and leads Yuko into a desperate attempt to regain her youth. She drinks a potion that begins a “de-aging” process, only to find out that once started the process cannot be stopped! Yuko and Satoru are forced to reexamine her life and their marriage, and their love for each other. And Yuko must somehow find a way to return to halt the process, or dire consequences await.
This touching story not only explores the question of lost youth but also takes a hard look at what it really means to love someone.