The official website of the Detective Conan television anime has confirmed the December 9 premiere date of Meitantei Conan Episode "One" Chiisakunatta Meitantei ( Detective Conan Episode "One": The Great Detective Who Shrank), the show's upcoming two-hour television anime special. The special will premiere at 9:00 p.m. JST on YTV . The official website is also streaming three trailers for the special.

Retailer Honya Club previously listed but later removed a description of the junior novelization of the special that indicated the premiere date.

The two-hour special celebrates the anime's 20th anniversary, and will retell what happened on the day Shinichi's teenaged body was transformed into that of a child. The special will add new material that was not in Gosho Aoyama 's original manga or "Jet Coaster Satsujin Jiken" (Roller Coaster Murder Incident), the first episode of the television anime two decades ago. The story begins when Shinichi sets up a date with Ran at the Tropical Land amusement park, and continues with Shinichi's encounter with Gin and the others at the park.