The Orient Express Investigation. Yui, Haruna, Reiko and Akiko are visiting Detective Net and decide to indulge in a "Mystery Tour" on the Orient Express, where they will have to locate the culprit of a crime. However, the virus corrupts the train, tampering with its brakes, and also decides to get rid of I.R., without which Yui cannot transform into Virtual. Poor I.R. he is thus locked up in the holds of the train by Virus, disguised as Professor Moriarty; the mystery that Yui and her friends will have to solve will be the disappearance of I.R. and only if they succeed in the enterprise will the train stop, otherwise it will end up crashing upon arrival. Yui senses that there is the hand of a Corruptor, but without I.R. she cannot transform; luckily, on the train she finds Floppy, disguised as Sherlock Holmes. Yui and Floppy manage to save I.R. and the girl can finally turn into Virtual and get rid of Virus. The problem now is to be able to stop the Orient Express, which, despite everything, is continuing its run; the situation is desperate, but with the help of Rescue, who thanks to his skill with traps identifies the unlikely hiding place of the emergency brake, the Virtuals manage to stop the train.