Boy/man detective adult

In order to take care of his younger brother, Nozomi runs the Gattendou (sort of a jack of all trades) convenient store. For his most recent job he'll be acting as the body double for a yakuza's son, therefore he'll be protected closely by a bodyguard.

From Nakama]
"I'll overwrite your memory."
Detective Yagi of Section 1 is teaming up again with his secret love interest and junior colleague Detective Amemiya, after a long period of separation. Yagi finds out that Amemiya still wants revenge on the violent ciminal who harmed him three years ago. The feelings never stop in this love crisis between Detectives!
"1 yen no Otoko" Sidestories
"Houtou to burai ~ kakugo" and "Houtou to burai+"
("Decadence and Delinquence: Resolution" and "Decadence an

Dog-complex policeman, Miyoshi, was captivated by the popular model, Kanae, who always looks like a stray dog. However, Kanae never paid attention to him, until a day Miyoshi managed to get close to him thanks to an incident. Will the love of these two naïve people be able to go smoothly?

From Fifay.net:
It was the roaring 20's, and the country was Japan. Bluecat, or Aoneko, is a debonaire aristocrat with too much money and leisure time. Along with his servant boy Tigerman, he dabbles in private detective work much to the chagrin of the r

Plot: A story about three men code-named Ace, King, and Jack, who work together at the Triple Detective Agency, and the man who wants to break them apart by taking Jack to New York.

An original manga by Nekota Yonezou based on the movie by the same name.

College student, Shirasane Yo, is living with his lover, Iwanami Kaito, a seasoned detective in Police Force Division One. Though Yo sometimes finds Kaitos appetite insatiable and sometimes extreme, they are deeply in love with each other. One day, Yo received a pair of movie tickets from work and invited Kaito for a date. When Kaito arrived at their designated meeting place, he was shot! Now the chase is on to find the culprit.

Paradise Love Scanlations]
A policeman and Kaitou's chasing love story. In the day, he's a gentle coffee shop owner. At night, he is a big charismatic thief...

Luna was one day saved by a man who trained him to become a killing machine, since then, our hero does mission for that guy organization as an assassin. One day he is given a mission which implies 'latching' onto a private detective by the name of Nishina Tougo with the objective of killing a scientist who created some dangerous drug...

Yajima met a gorgeous young man, Ryo, when he was investigating a case. He was mesmerized by Ryo’s eyes and got his badge stolen instead. Who is Ryo? What does he want? And who was the man living in Yajima’s heart? The tormenting memories are coming back again…

Yamato runs a detective agency that will use any means to get the job done, no matter how unconventional. His three misfit employees are more than his teammates, they’re his family too. Also tells the dramatic and surprising story of Yamato’s past.