Drunk Detective Iron Masked Cross

(from ebookjapan):
The "Iron Masked Cross" is a phantom thief who appears and disappears from banks and wealthy families across the country. There was a father and son detective pursuing this thief. The son, Gen, an enthusiastic and talented ace of the Investigation Section 2, goes missing while on a solo pursuit of the thief. Six months later, Gen returns to find that he has turned into a coward who drinks all the time! What is the case that the former detective, who was fitted with an iron mask that can never be taken off again, is chasing? ...... Everyone lives hiding his or her true face. The suspense of sadness and loneliness begins!