What long-running Japanese anime series follows the brilliant high school detective Shinichi Kudo, who, after being poisoned by the Black Organization, shrinks into a child's body and takes on the alias Conan Edogawa to continue solving crimes?

The long-running Japanese anime series that perfectly fits this description is Detective Conan (Review). This beloved mystery franchise centers on the brilliant high school detective Shinichi Kudo, who, after being ambushed and poisoned by a mysterious criminal syndicate known as the Black Organization, finds his body transformed into that of a young child. To protect his identity and continue his investigation, he adopts the alias Conan Edogawa.

The series, also known as Case Closed in some English-speaking regions due to legal considerations, originated as a manga written and illustrated by Gosho Aoyama. It began serialization in January 1994, with the anime adaptation premiering in January 1996. Despite its real-world longevity, spanning over a thousand manga chapters and anime episodes, the in-universe timeline has progressed very little. The creator has stated that less than a year has passed since Shinichi's transformation, maintaining a unique "floating timeline."

As Conan Edogawa, the shrunken detective lives with his childhood friend Ran Mouri and her private detective father, Kogoro Mouri. Using his sharp intellect and an array of gadgets provided by Professor Agasa, Conan secretly solves countless cases, often by tranquilizing Kogoro and using his voice to present the deductions. His chosen alias, Conan Edogawa, is a clever nod to famous mystery writers Arthur Conan Doyle and Ranpo Edogawa, reflecting the series' deep roots in detective fiction. Its enduring popularity has led to numerous animated feature films, video games, and spin-off series, making it a significant cultural phenomenon in Japan and around the world.