Detective Conan OVA 9 - The Stranger from Ten Years Later

Conan Edogawa is sick and has to stay home with a cold. He overhears Sonoko Suzuki telling Ran Mouri to dump Shinichi Kudo and instead date Dr. Tomoaki Araide. Conan gets angry over this, and falls asleep, waking up to a phone call from Ai Haibara. She tells him that she has created an antidote for him to try out, for testing purposes. Conan takes the antidote, and passes out. When he wakes up, he is Shinichi Kudo again! However, Haibara is gone, and everything looks strange.