Alternative:
世界最高の暗殺者、異世界貴族に転生する; 世界頂尖的暗殺者轉生為異世界貴族; Лучший в мире ассасин, переродившийся в другом мире как аристократ; Le meilleur assassin, réincarné en un aristocrate dans un autre monde; Sekai Saikou no Ansatsusha, Isekai Kizoku ni Tensei suru; The World's Best Assassin, Reincarnated in a Different World as an Aristocrat; The World's Finest Assassin Gets Reincarnated in Another World; The World’s Finest Assassin, Reincarnated in a Different World as an Aristocrat; The World's Best Assasin, to Reincarnate in a Different World Aristocrat; The Best Assassin, Incarnated Into a Different World's Aristocrat