The Darkness of the Prefectural Police: Part 1 Meitantei Conan : Season 42 Episode 7

Kogoro, Conan, and Ran visit the Kawanakajima battlefield where they run into Detective Yamato and his associates of the Nagano Prefectural Police. During their tour, they visit the Chikumagawa River where a severed head pops up to the surface, only to be that of one of the Nagano detectives.