Hello everyone!
I've googled and searched about everything I could, and I can't remember the name of this manga, nor find anything close.

It's Yakuza story based, male lead with a female body guard. However, the main is engaged already, and the fiance keeps saying she's the "seisai", and the manga then ends up with that fiance/seisai, in competition with daughters of the other branches, including the heroine bodyguard, for the position of seisai.

Also, the female bodyguard, her mother was a someone highly respected, but gave her up to be cared for by friends (or maybe it was someone related..). It may be a bit gender-bender also, since the heroine's hair is very short and boy-cut, and most of the yakuza men don't' find out until her outfit is torn and ripped during a battle.

Pairing-wise, the heroine and the male lead do end up together, but I remember a love triangle with a cop liking the heroine. And the fiance of the lead ends up liking the cop's partner, who is a bit of a womanizer, and she has a prosthetic arm after having it cut off during a battle.

I hope I've given enough detail for you guys to help me x.x
The manga should be completed too.

You might have already looked at this, but the details sound very similar to tokyo crazy paradise.
A cop does end up liking her, and due to safety reasons she was disguised as guy.

It is!
No wonder I have having a hard time, I thought the title was in japanese. Tokyo Crazy Paradise didn't sound familiar to me.

Thank you very much!