The Devil's 7 Candies

There was once a demon phenomenon they later called "The Devil's Treat", a sudden demon appeared and destroyed the city with rage. Huridth, the boy who's responsible don't remember how he did it. An academy took him in while knowing his secret. Later his father asked help from Huridth. But in order to do that he must first collect the "7 candies". Can Huridth do such task? Can he save his father?