The culprit is Kyota Honma. After the case, Conan and Eisuke have a one-to-one conversation, and Eisuke reveals he's actually known Conan is Shinichi since the very first time he's met him, noticing his great intelligence and his voice-changing bowtie he used to impersonate Kogoro. Though, Eisuke isn't aware of the all APTX story. He says he feels disappointed Ran's lover is still around, given he loves her too. Eisuke decides to move to America in order to join CIA and resume the work of his sister and father.
