Detectives These Days Are Crazy! English Subbed

Summary:
In the detective business, everyone knows the name Keiichirou Nagumo. Back in high school, he was called a genius for cracking tough cases that even the police could not solve. But those days are long gone—or so the rumors say. However, one day, an unexpected visitor barges into his office: Mashiro, an energetic high school student who demands to be hired as his new assistant.