Kidnapped by the Demon King and imprisoned in his castle, Princess Syalis is...bored.

Twilight, Zeus, and the princess must face a truly harrowing challenge--attending Goodereste Royal Academy incognito! Things quickly go awry when they encounter a group of demon-obsessed students, a mysterious grimoire, and the most dangerous enemy they've ever faced. Then Demon Cleric deals with some non-Syalis feels, Odile's vacation fail ends with him getting eaten by a whale, a princess possessed by a father proves a bother, and more!