Manami is just starting fifth grade with her friends, when her new homeroom teacher shows up and introduces himself as the King of the Underworld (Diablo de Mon). Is Manami's homeroom teacher really a demon lord?! What's going to happen to the class of fifth-graders from now on? Watch Manami and her friends as they adjust to their new homeroom teacher.
-- Written by Miki Yoshikawa (the author of Yankee-kun to Megane-chan)