Is Meitantei Conan: Haibara Ai Monogatari - Kurogane no Mystery Train hentai?
English title: Detective Conan: Ai Haibara's Story - Jet-Black Mystery Train
No
Rated PG-13 (Teens 13 or older) on MyAnimeList and not tagged as Hentai.

Movie · 2023 · 1 episodes · PG-13 - Teens 13 or older
Detective, Mystery, Shounen
The movie will focus on Ai Haibara's past and will reconstruct the Mystery Train arc from the television anime, which shows Haibara and Conan meeting for the first time. The movie will also include scenes from the Kurogane no Submarine (Black Iron Submarine) movie. (Source: MAL News)
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