Iron Masked Detective Gen

(from ebookjapan):
Always in a drunken stupor, private investigator Gen Jumonji is a former police detective of the Tokyo Metropolitan Police Department. He is a man who has given up on the pursuit of ordinary happiness, having been fitted with an iron mask that can never be taken off again. One day, he receives a request from his former teacher from his college days. A young man named Majiro Shirakami, the subject of a parapsychology study, was murdered in a locked room. In order to solve the case, Gen and his mentor visit the Shiragami family home in Nagano Prefecture, but the Shiragami family members are murdered one after another. ......? A masterpiece of suspense, a sequel to "Drunk Detective Iron Masked Cross"!