This movie is "Demon Slayer -Kimetsu no Yaiba- The Movie: Mugen Train" and story line : Tanjiro Kamado, joined with Inosuke Hashibira, a boy raised by boars who wears a boar's head, and Zenitsu Agatsuma, a scared boy who reveals his true power when he sleeps, boards the Infinity Train on a new mission with the Fire Hashira, Kyojuro Rengoku, to defeat a demon who has been tormenting the people and killing the demon slayers who oppose it!.