Amakawa Haruto, a twenty year old university student, loses his life when the bus he is on gets into an accident. As his consciousness begins to fade, his one regret is not telling his childhood friend, Miharu, how he felt. She'd disappeared after their high school entrance ceremony. Now we move to the slums of the Kingdom of Beltrum. In a corner of a filthy shack, a boy named Rio moans and wakes from a nightmare. He has lived only to take revenge upon a certain man, but now, in his mind, suddenly there are flashes of another version of himself living in a world he's never seen before—the memories of Amakawa Haruto.

As a reward for saving the kidnapped Princess Flora, Rio has been enrolled in the primary school branch of the Beltrum Royal Academy. However, the students at the academy are mostly the children of royalty and the nobility, and they do not welcome the orphaned Rio. With so many scornful gazes turned toward him, there is one person who worries for him—Celia, a girl of twelve who is nonetheless, at her young age, the lecturer in charge of the primary school. As Rio cannot read, Professor Celia begins privately tutoring him after school.