Detective Conan: Shinichi Kudo's Written Challenge

I'm the Killer! Three Independent Murderers? Reveal the Mystery of the Disguised Murder!

Machiko Sonoda, Ran's computer school teacher and Kogoro's drinking buddy, is found lying still – presumably dead – behind the closed shutter of Beika City Bank's safe-deposit box floor. There is a warning – the moment the shutter is open or the police make a move, the bank will be exploded. When asked for the murder culprit, all three suspects – Yuzo Nimura, Yoko Sakai and Ryosuke Hasegawa – raise their hands. Can Shinichi find the true culprit and prevent the 'explosion'?