The World's Finest Assassin Gets Reincarnated in Another World as an Aristocrat - S01

The world's greatest assassin had sworn lifelong allegiance to the organization that raised him. But despite his loyalty, that same organization moves to silence him, and it ends with his death. Drowning in frustration and regrets he can no longer hold back, he finds himself before a goddess drawn to his exceptional skills. The goddess offers him reincarnation into a magnificent world of swords and magic so he can carry out a crucial mission: stop that world's destruction by killing its hero. He accepts the goddess' request and is reborn as Lugh Tuatha Dé, son of a noble family of assassins serving the Alvan Kingdom. Under his father's guidance, Lugh learns new assassination techniques that differ greatly from the cold-blooded, unsympathetic killing style of his previous life. His other talents bloom as well, letting him meet new allies and acquaintances. Even so, Lugh knows his efforts are far from enough, because a monumental adversary like the hero can only be defeated with perfection.