Detective Conan: Episode "ONE" is a special anime that premiered in fall 2016, produced by TMS Entertainment.

About the production: the story comes from a manga, there is 1 episode of about 95 minutes and its current status is "finished".

Its main genres are action, adventure, drama and mystery, with themes such as Age Regression, Detective, Police and Shounen.

On AniList, Detective Conan: Episode "ONE" has an average score of 81%, a very good score, and appears on 7,228 users' lists.

A special commemorating the 20th anniversary of the anime series. The special is a retelling of how Kudo Shinichi was transformed into a child. It all started when Ran lost her smartphone. Shinichi promises to replace it, but the high schooler is already making his name as a consulting detective for the police; when he abruptly leaves her karate tournament to skillfully solve a high-society murder case, Shinichi's going to have a take Ran on a special date to get back on her good side. A colorful amusement park beckons — and so does a horrifying act of homicide! (Source: Anime News Network, TMS Anime)

Official synopsis from AniList.