A royal tutor is the person in charge of a prince's education—a title only given to the most outstanding teacher in the country of Grannzreich. Heine Wittgenstein, an adult with a child-like appearance, is asked by the king to teach four of the five princes, as their former tutors gave up on them. Determined to turn the young men into proper heirs to the crown, Heine accepts the challenging task.

When the princes greet Heine, their noble facade falls quickly and each of them shows their true personality: arrogant Leonhard wants nothing to do with tutors; stuck-up Bruno thinks Heine is not qualified for the job; flashy Licht only goes with the flow of his elder brothers; and stoic Kai is indifferent to the matter. However, Heine is set on educating his problematic new students—regardless of how they feel about him.