From Renta!

Shimojo is bored to death of life always going his way. His thrill-seeking led him astray and onto the path of a mafia-like degenerate. Nevertheless, he still feels like his life is on easy mode. One evening, he runs into a filthy excuse of a man. Said man turns out to be Kuse, a guy from his high school days and the only person to ever make Shimojo feel defeated. Shimojo becomes enraged upon seeing the deadbeat Kuse, having wanted to be the one to ruin the other man. Ignoring his unpleasant nostalgia, Shimojo offers Kuse money in exchange for being his pet. Now that the lives of this intelligent, sleazy gangster and the homeless, leeching scumbag are once again entwined, just what does the future have in store...? The world that ended when they were teenagers starts anew!

From CM Scans & Fujoshi Bitches
“I’m a winner in life and knew nothing of losing.”
“From the start, till the end, he’s my rival.”
Shimojou can have whatever he wants but deep down, finds life boring.
Constantly searching for a thrill, he wanders off the path of an elite and descends into life as a yakuza-like lowlife.
Then one day, he comes across a man who’s a filthy piece of garbage.
This is the man, who during his youth, was the only person who has given Shimojou the taste of defeat: Kuze.
“Bringing you down, is my mission.”
“If you’re doing this for money, how about letting me keep you as a pet, then?”
An intellectual ersatz yakuza lowlife and a homeless parasitic piece of garbage, their life together begins again, but just where will the future lead them…?
The world that stood still during adolescence is carving out new tracks starting now!