Roar in the Big City

Jinnai, an enthusiastic cop, is now at a loss. First, a gruesome murder case he's working on is assumed by people to be the work of a demon. Then, his unit is getting help from a special agent sent by FBI to solve this case. What kind of special agent? An agent that specializes in handling demons? Great! And that agent is just a high school girl? What is her unit called again? G-man.

Things get more complicated when the witness of the crime is also a beautiful woman, and now both of them have fallen in love with him. Jinnai tries to be strong, but will he be able to resist them? And there is also another G-man who fell in love with that high school girl? Will Jinnai be able to handle this mess and solve all the cases concerning demonic entity at the same time?

(from mangaupdates)