Roman-thriller cerita

This is the story of a young man named Kotaro Nueno,He is 18 years old and his dream is to become a detective.But one day, a serial killer murders his father in a room so Kotaro is determined to avenge his dead father. The task gets complicated when he meets an entity that calls itself the mystery demon. the mystery demon is in search of the ultimate mystery and makes a pact with Kotaro, both of them will solve the mystery. the two of them will solve investigations that are quite supernatural and disturbing.