Tanjirō 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, Kyōjurō Rengoku, to defeat a demon who has been tormenting the people and killing the demon slayers who oppose it!

The Hidden Dungeon is a place of legend where rare treasures and items are hidden. Nor, the third son of an impoverished noble family who's lost the one job offer he had, was lucky enough to hear about this dungeon. He then acquires a skill that allows him to create, bestow, and edit skills... and in order to use it, he needs to accumulate points by carrying out such tasks as eating delicious meals and doing sexual things with alluring members of the opposite sex.

Nene and the ghost of Hanako-kun want to stay out of trouble at Kamome Academy, but shenanigans follow them wherever they go.