The halls of their old high school echo with the ghosts of past brilliance, a place Sanosuke Saraki thought he’d left behind for good as a university student. But fate has a wicked sense of humor, pulling him back into the familiar classrooms and corridors for a new part-time job. Here, amongst the eager faces of freshmen and the resigned sighs of seniors, one figure stands out, a living legend wrapped in a tragic irony. Koharu Kobachi, once a celebrated prodigy, now walks those same halls as a dreaded "5th year high school student," stuck repeating her final year for the second time.

For Saraki, a guy barely scraping by, reuniting with his former classmate, the brilliant genius he once looked up to, is a jolt. But this isn't a nostalgic trip down memory lane. His new role comes with a secret, impossible mission: ensure Koharu finally graduates by the end of the year. How did someone so incredibly smart fall so far, and how can a poor university student possibly guide a genius back onto the path to graduation?