The culprit is Sanpei Kokuri. The motive was that Hotta used his late sister's corpse for his show. A few years ago Kokuri's sister committed suicide in the mountains due to a break-up. But her body was never found. Later Hotta was making a show in the mountain (most likely in connection with a missing person case, that Conan and Kogoro discussed in the taxi) and 'found' the body claiming to have 'felt' it's spirit. Kokuri realized that Hotta must have found his sister's body a long time ago, but instead of reporting it to the police, he had buried it to use it in his show. So he killed Hotta in revenge for having humiliating her.
Masumi calls Mary "Mama", indicating that she is her mother.
The only information that the victim had was that he believed Asaka to be a woman. He was going to pretend that he had summoned Kohji's spirit and have it say that a woman was going to kill him. The culprit said that someone saw Asaka holding "that small mirror". Mary consider that detail as 'boring'
Conan considers that if Asaka is Rum, then perhaps what Haibara said about being feminine refers to looking girly on the outside but strong like a man on the inside. If Rum had been a bodyguard 17 years ago, then they must be old now. Conan also ponders the possibility that Mary is Rum after having shrunken, being girly yet strong and older than she looks.
Later, Gin and Vodka discuss about the murder case and The Case of Kohji Haneda. Gin comments that Rum screwed up in that case, in fact Gin is intrigued that Kogoro went to investigate the murder case and stick his nose in the Organisation's matter. Gin says " It's like encountering a demon in the darkness, if that guy is the demon we should finish him off while he sleeps".
