Realizing the piano playing they hear is a recording, they enter the piano room. Conan notices the piano chair was set to a child's height and deduces where the boy is. He has the Detective Boys sing a song in the piano room and catches the boy watching them and befriends him. The boy, Keita Onoda, is a piano prodigy to which the kidnapper abducted to allow his daughter to win a piano competition. Conan also reveals the dairy entry is out of order due to Keita's tampering and that the kidnapper felt increasingly guilty as the days went on. After reading the last page in the dairy, they realize the kidnapper plans to suicide in the bathroom and manage to save him. In the aftermath, Keita's mother does not push charges due to Keita's defense. The kidnapper's daughter meanwhile, revealed she skipped the piano competition as she was worried about Keita's disappearance.
Conan remarque que la chaise du piano est réglable et qu'elle peut être utilisée par un enfant. Les garçons détectives tentent ensuite de découvrir où se cache le petit garçon mentionné dans le journal.
Conan nota che la sedia del pianoforte è regolabile e può essere utilizzata anche da un bambino. I Detective Boys cercano, quindi, di scoprire dove è nascosto il ragazzino citato nell'agenda.
Deciden entrar en la sala del piano y se encuentran a un niño que es un prodigio tocando el piano. Dijo que le secuestraron para que la hija del secuestrador pudiera ganar un concurso. Después de investigar descubren que el secuestrador se iba a suicidar en el baño y consiguen salvarlo.
Decideixen entrar a la sala del piano i es troben un nen que és un prodigi tocant el piano. Va dir que el van segrestar perquè la filla del segrestador pogués guanyar un concurs. Després d'investigar descobreixen que el segrestador s'anava a suïcidar al bany i aconsegueixen salvar-lo.
