Help!!!

I’ve been searching for this manga FOREVER!!!
It goes along the lines of this: son is orphaned after parents are killed by a gun man. Dad was like this assassin/treasure hunter person. He scored a big pay day(like 1,000,000$ or something) that everyone was after. After parents murder, son went into the same line of work like dad. Son liked throwing things were he was give a deck of special cards that were made of something harder then cardboard. Secondary character is also male where he is an up an rising assassin. Him and the main character take a job to find this recording of a dead dude. But becuase the main character sound a lot like the dead dude, this chick locked him up in this sound proof bunker. Where he got a high fever and was about to die until the secondary character finds him.
I know this is a shoty summary of the manga but bare with me. I know it’s not a yaoi. Kinda school life, actiony, not bl although the characters hint at it. Kind of a bromance