Kindaichi Shounen no Jikenbo

Synopsis

Hajime realizes that the red torii referred to in the song would now appear black because of the geyser. 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. They enter the cavern containing the treasure of gold and jewels guarded by a huge Yamawara statue. Eisaku Iwata, the former butler, then prepares to shoot the remaining members of the group to keep the treasure for himself, but Kyoko Kaya shoots him in the shoulder and reveals that she is a police officer who is chasing Iwata for suspected murder and insurance fraud. Iwata makes a grab for the gold which topples the statue, killing him and causing the cavern to collapse, burying the treasure in the process. Hajime saves Koichiro who reveals that he met Midori and how he had planned revenge against Mimasaka for the death of his father, but he fell in love with Midori, only for her to commit suicide over her father's actions. Later, Koichiro Saeki is arrested for his crimes. Although what was in Kyoko Kaya’s box remains unknown.

(Source: Wikipedia)