Apart from the aforementioned salary, if a police officer is unmarried, the Metropolitan Police Department requires them to reside in the designated single dormitory.,PS: A 22-year-old detective is possible, the protagonist's birthday is set later, so he is still 22 after graduation, besides, that's how twisted the occupation group is.,Besides, I wonder if you've seen Monogatari Series, where Araragi Kun became a deputy police superintendent at 23 after graduating from university. His sister joined the police force as a patrol officer while still in high school.。