Hajime realizes that the red torii referred to in the song would now appear black because of the action of water. However, Hisayoshi Yaogi has also solved the mystery and finds the location of the treasure, but when Hajime leads the others there, they find him dead. Hajime deduces that Midori Mimasaka is the killer, but she is in fact Koichiro Saeki, Professor Saeki's son...