I'm Quitting Heroing manga volume 4 features story by Quantum and art by Nori Kazato and Hana Amano.

Leo has officially joined the Demon Queen’s army to foster peace between humanity and demons. But now he has a new challenge on his plate—clearing the underground dungeon inside the Demon Queen’s castle, which is chock-full of steamy tricks and traps! And on top of that, the Demon Heart series returns to life…?!