Ghost or Trick

In a certain city in a certain country, there was a detective agency. All the detectives belonging to it were strange. This was because they only investigated cases related to ghosts and monsters. Then a request comes in for them: a ghost appears at the villa of a nobleman. Jake or Jessica, who has been assigned to work as a detective's assistant for only seven days, begins investigating the ghosts with Arthur, a detective of beauty. Is it a "real ghost" or the work of a "human"? The player's choice will guide Arthur.