Detectives These Days Are Crazy GN Vol 02
Keiichiro Nagumo may have been a super great detective at one point, but now that he's in his thirties, he's just some dude. Appearing before this outmoded private eye is Mashiro, a high school girl brimming with youth, and the pair tackles cases together as they contemplate their generation gap. Until one day, a rival (?!) detective comes to them with an SOS.