Contractor

When Liang Feng was six years old, he was taken into a mountain hut, where an ugly old witch forced him to sign a contract. Sixteen years later, that contract was triggered. "Devil? Guardian? Supernatural ability? Witchcraft? What are these?" "Why are you all so powerful and I'm just a weakling?" (This book is roughly about an ordinary young man who suddenly realizes that he is living in a world shrouded in a contract, and strives to survive in order to protect her and himself.)