Detective Conan: The Stranger From 10 Years Later

One day Conan has a fever when Haibara calls him. She lets him test the new antidote for APTX 4869. Conan turns back into Shinichi, but things seem a little weird. Shinichi realizes he's forgotten his memories for the last 10 years and learns that he hasn't been able to defeat the Black Organization and that he is still Conan, now only 17 years old. He's shocked when he hears that Ran has decided on Araide-sensei's proposal. He runs out to search for her and tell her the truth.