Vain: Return of the Demon King

They betrayed you, and after all you did for them, you killed the Demon King and saved this world, and how do they repay you, Death. Your no stranger to death even as they cleave your head off you await what comes next, but just like when you were first reincarnated, the end is not here for you yet. You wake up as the child of a peasant girl, ready to take your revenge.