Tanaka dismisses Mitsuhiko's accusation as his imagination and the police continue their investigation. Agasa notes that his hammer is missing and Conan discovers an officer found the hammer in the woods. Conan later finds the rumored knife with the red handle and shows it to the police. None of the weapons reacted to luminol and leaves the officers stumped. As Conan investigates he realizes who the murderer is. Disguising his voice as Agasa, Conan first reveals Kahara is a fake name and that he is actually Tanaka's grandson in disguise, Shouta Tanaka. Since Kahara lived in the house before, he would have used the knife in the shed and is thus, eliminated as a suspect leaving Adachi as the culprit. As evidence, Conan reveals Adachi had his shoes on when he was by Ooba's body while everyone ran bare feet to investigate the screaming. As for the weapon, Conan reveals Adachi used the hammer to break apart an obsidian rock found in the fish tank for the murder; he then concludes the weapon used for the murder should be in the tank. Adachi professes to the murder revealing Ooba tricked his parents into furthering their debt and murdered her in vengeance. Tanaka gives her grandson the knife and her grandson promises to start visiting her again. A month later, Conan spots Shouta working as a chef with the knife his grandmother gave him.