Blade transfers into Rosewood Academy, a school built to train heroes for a demon war that technically ended generations ago, and immediately draws the attention of Arnest Flaming, the school's undefeated top student. Blade matches her strength move for move despite acting like he's not trying, and the King's personal request that Arnest look after him only makes her more suspicious of what he's hiding about the era of the original Demon Lord's defeat. This manga adapts the original light novel series.