Sekai Saiko no Ansatsusha, Isekai Kizoku ni Tensei Suru 1 (Kadokawa Sneaker Bunko) [Light Novel]

[Machine Translation] The world's greatest assassin is reborn as the eldest son of an assassin noble family. He has only one mission in the other world: to kill the "hero" who is predicted to bring misfortune to mankind. (In order to complete this noble mission, the assassin, together with his beautiful followers, will perform dark deeds in the other world. The assassin's extensive knowledge and experience, which have made all kinds of assassinations possible in the modern age, and the secret arts and magic of the assassin's family, which is said to be the strongest in the other world, all work in synergy. All of these factors create a synergistic effect, and he grows into an assassin who has no equal in the history of the world. ( Funny, I never thought I would be reincarnated and assassinate again. ) The reincarnated "legendary assassin" rises to even greater heights! Assassins' fantasy that pushes the limits!

世界一の暗殺者が、暗殺貴族の長男に転生した。彼が異世界で請け負ったミッションは只一つ。「人類に厄災をもたらすと予言された“勇者”を殺すこと」その高貴なる任務を完遂すべく、暗殺者は美しき従者達と共に異世界を暗躍する。現代であらゆる暗殺を可能にした幅広い知識と経験、そして異世界最強と謳われた暗殺者一族の秘術と魔法。そのすべてが相乗効果をうみ、彼は史上並び立つものがいない暗殺者へと成長していく―。「面白い、まさか生まれ変わってもまた暗殺することになるとはね」転生した“伝説の暗殺者”が更なる高みへと駆け上がる!限界突破のアサシンズ・ファンタジー!!