The world's greatest assassin had sworn lifelong allegiance to the organization that raised him. However, despite his loyalty, that very same organization takes action to silence him, ultimately leading to his demise. Drowning in frustration and regret he can no longer suppress his emotions, he finds himself in an audience with a goddess attracted by his exceptional skills. The goddess offers him reincarnation into a magnificent world of swords and sorcery so he can perform a crucial mission: Prevent the world's destruction by slaying its hero. How will his new life begin?