The Eldritch Files

In 3 years, Han Su has been brought backed in dreams 17 times to the castle where he and other children were kidnapped. His action will change the reality, with the victims he saved coming back to life and losing memories of the tragedy. He will also acquire different superpowers from the thirteen monsters in the building. It seems to him a infinite loop only can be broken after he managed to save all other victims... — Description from novelcodex.org