I'm Really Not the Star of the Police World

Kitagawa Ryusei, a prospective cadre of the Port Mafia, wakes up to find himself in a strange world and is about to enroll in a police academy.
Kitagawa Ryusei: Seriously??
Can a Mafia member like him really become a good cop??
That is until he meets five troublesome peers.
Some look fiercer than him, some claim to be more destructive, and some are probably more stubborn…
Maybe it’s not impossible?
With the principle of loving whatever job he does, Kitagawa Ryusei declares: Sorry, boss! I’m switching careers to become a cop!

…

Except for two peers who went missing after graduation, Kitagawa Ryusei is quite satisfied with his thrilling career in Tokyo. Using his abilities to stir up trouble (crossed out), he successfully shines in the police world, earning the title of “Star of the Police World,” and leads his subordinates further down a path filled with “Port Mafia” vibes.
—Until a certain evil force sends a blond guy to try and gather information on him.
Kitagawa Ryusei: …Zero, your smile is terrifying.
Kicking lunchboxes, blowing up distilleries, and giving the black-clad guys from Conan a taste of the Port Mafia’s shock!