Second Life of Assassin and Become Hero in Parallel World

Looking for anti-mainstream isekai? Try to read my novels!! Warning: This novel is slow-paced, I hope you don't bored. Synopsis: A child was raised to become a professional assassin.That child doing that to avenge the death of his parents. But he realized that he had been working for the murderer that he was looking for. After he had done various dirty things and killed many people, he eventually realized the fact. Even so, he managed to get his revenge but lost his life as a price. But not the realm of death awaiting him, but a new world. With various complicated situations, various problems will come to our MC. Author Note : -I apologized for my terrible grammar and any typo. -This is my first time writing a novel. I hope u will kindly give me support like critics and advice to improve the story quality. -I don't own the image on the cover