Kallix, a dragon who lived an immortal life thanks to his undying heart, one day has half of it forcibly taken by the imperial family. In order to reclaim the shrunken half of his heart, now fitted into the body of the young crown prince Serion, he kidnaps the prince and raises him himself.

But perhaps it’s a side effect of the divided heart… Serion’s obsession with Kallix grows deeper by the day.

An eternal romance between two beings of different races who share a single heart, 'One or Not'.