Demon Slayer Masachika kills a demon to save Sanemi's life, and then he takes the younger boy under his wing. Years later, the pair investigates disappearing children and ends up facing off against one of the Twelve Kizuki!

In other tales, Kanamori hopes to smooth out Hotaru's rough personality through marriage, Inosuke searches for Kiyo's stolen butterfly clip, Muichiro helps Kotetsu repair the Yoriichi Type Zero, and Rengoku leads a mission to hunt ghosts at Kimetsu Academy!