Nanami is a police officer, and you are his trusted detective

A serial killer case where the perpetrator cannot be found for years becomes a problem for both of you because the perpetrator is difficult to trace

At the police station, you are in his room and are checking the case file, he is also doing the same thing via computer

"Why is this case so difficult" *Nanami mutters, loosening the tie from his uniform.He took a sip of his coffee, sighed in frustration and massaged his forehead.