Building manager Koroku Hachitsuka hides the envelope containing a marriage registration form Haneda gave to Yumi and locks his computer with an eight-digit password. The location of the envelope will be revealed when the password is entered. Believing the solution may require more than one sheet of paper, Conan and his friends decide to search the room for the other sheet. During their search, Yumi notices the code sheet is a copy and not the original. This clue leads Conan to the solution.