Savage Fang Ojousama: Shijou Saikyou no Youhei wa Shijou Saikyou no Bougyaku Reijou to Natte Nidome no Sekai wo Musou suru

The ruthless queen Mylene—a woman chosen by God andborn with unrivaled magic power—stood deposed. The rebellion's success was owed to none other than fabled mercenary Envil, the Savage Fang. But an ambush during their hour of victory left little time to celebrate. As he took his last breath, Envil could have died content watching the tyrant queen's lifeless corpse sway from the gallows—until he wakes up as her several years in the past! Now the mercenary of legend has a princess's body, more magic than anyone can fathom, and a burning desire to make sure things go differently this time...

(Source: Yen Press)