“The World’s Finest Assassin Gets Reincarnated in Another World as an Aristocrat” is a isekai light novel series written by Rui Tsukiyo and illustrated by Reia

here is the Summary for the 1st season

The story revolves around Lugh Tuatha Dé, a legendary and unparalleled assassin in his previous life.

He was the best in the business, feared by all who knew of him. However, after a successful career filled with countless assassinations, Lugh is eventually betrayed and killed by someone he trusted.

But instead of facing an eternal slumber, Lugh finds himself reincarnated in a completely different world. To his surprise, he’s not reborn as a commoner or a hero, but as a noble aristocrat named “Toge Kiryuu.” This new world is filled with magic, fantastical creatures, and political intrigue.

Given his deadly skills and combat expertise, Lugh/Toge Kiryuu quickly adapts to his new life as an aristocrat. However, he is not content with a life of leisure and luxury. Lugh seeks to uncover the mysteries behind his reincarnation and the reason for his betrayal in his previous life.

As the story unfolds, Lugh uses his assassin’s skills to navigate the treacherous waters of the aristocratic society and the hidden dangers lurking in the shadows. He also forms alliances and confronts enemies as he strives to achieve his goals and unravel the secrets of this new world.

Throughout the series, readers and potentially viewers (if an anime adaptation has been released) can expect a blend of action, fantasy, mystery, and intrigue as Lugh/Toge Kiryuu strives to become the world’s finest assassin once again, even in a world of magic and nobility.