Aki reveals that Kouei is in deep in debt for gambling and becomes the main suspect, but Sakon reveals that the arrow was triggered by a timer, making anyone the potential killer. Because the crossbow was on a timer, they cannot determine if Kujou or Naoto was the target. Naoto finds a threatening note in his room, fired by the same crossbow that killed master Kujou, and then Aki is found stabbed to death by someone wearing an Oni mask. Following the attacker, they find Kouei dead in a crashed car with the Oni mask and costume, indicating that may have been the murderer all along.