Jigokudo Spiritual Press.

Upon rescuing a friend who is being held captive by a wicked classmate and his gang of bullies, 11-year-olds Tetsushi, Yuusuke, and Ryoji unexpectedly find themselves entwined in a supernatural battle against the forces of hell. Armed with courage, wit, and three magical charms given to them by a mysterious hermit, they set out to thwart the evil in a quest, which takes them to the depths of hell and brings them to a final battle with the god of death himself.