At the theatres, the Detective Boys run into Shiratori who is depressed Sato's affection is being directed at Takagi. Shiratori reveals that he is bound to Sato because of an encounter he had with her in the past. Shiratori explains Sato as a young girl stood up to two thieves by herself. Shiratori helps her stop the thieves and in return receives from her a drink with paper folded sakura. Conan questions whether that girl was actually Sato as their personalities differ greatly. During the movie, Shiratori runs into a woman named Nami Kasakura who offers him a drink with paper folded sakuras causing Shiratori to consider the possibility she was the girl in the past. After the movie, Kasakura tells Shiratori she is being stalked and asks him to investigate. At her apartment, Kasakura's boyfriend is found dead.
Murder
Location:Apartment
Victim:Yoshiro Somei
Cause of death:Blunt-force trauma
Suspects:Nami Kasakura
Conan suspects Kasakura but her alibi supposedly states she was at the theatre the whole time.
Part 2
Shiratori has Takagi search for the drinks at the theatre and to bring them to the apartment.
Shiratori reveals his deductions and explains that Nami Kasakura drugged him with sleeping pills and placed her tuque on him to create her alibi by having Shiratori impersonate her. Takagi arrives at the department and shows them Shiratori's drink. Shiratori reveals that he had broken a piece from the flower design yet all the pieces remained on his drink revealing that Kasakura switched his drink while he was asleep to hide the fact that there were sleeping pills in them. As further evidence, Shiratori explains that there was a white string on his head from the tuque meaning his hair should also be found on Kasakura's tuque. Kasakura confesses and reveals that her boyfriend had been cheating on her for the past two years and she killed him in vengeance for giving her mother's ring to another woman and for wasting her seven years. Shiratori, saddened that the girl of his past has become a criminal, is cheered by Ayumi who offers him paper folded sakura's and repeats the same thing the girl in Shiratori's past says. Ayumi explains she learned that from her teacher Sumiko Kobayashi causing Shiratori to realize Kobayashi was the girl from his past.
