The world's finest Assassin accepts the Goddess' request to assassinate the Hero. After defeating the Demon Lord and saving the world, the Hero will then use his power to destroy the world. The Goddess wants the Assassin to be reincarnated in another world and assassinate the Hero in order to save it. After being betrayed and killed by his client in his previous life, the Assassin accepts her offer in order to relive his life in a new world, but--
after experimenting on 
numerous death row criminals.
بعد تجاربٍ على كثير من المجرمين
المحكوم عليهم بالموت
tras experimentarlo
en criminales condenados a muerte.
pour mettre au point
cette opération spéciale.
após fazer experiências com vários
criminosos no corredor da morte.