While Harumi and her class are on a school trip to an amusement park, they are attacked by a Squid Demon named Walter Geso. Despite taking Yukiko hostage as well, Enma manages to free all the hostages and defeat the demon, albeit destroying the park in the process. Afterward, Yukiko and the others explain to Harumi how they were summoned by the Great King Enma, Enma's uncle, to travel to the human realm to stop escaping demons. Their first case involves fighting demons named Snakejar and Shock Willow. After the flashback, Harumi reveals that he teacher, Ms. Chiko, had been acting weird recently, and upon investigating her, they find a strange mark on her leg.