House of Kou's maiden Reirin is famed as "His Majesty's Butterfly".
But not only does she swap bodies with House of Shu's maiden Keigetsu, due to the girl's own machinations, but must also face execution for injuring her own self.
However, with her nerves of steel, built over a lifetime of walking side by side with death due to her body's frailty, she...! And more than anything, she's elated to have finally attained a healthy body?!