Help mehhhh!!!

So this is a manga I've read a long time ago, and as far as I can remember this is how the plot went: there was an isolated island (I think), and in that island there were many drug dealings, killings, etc. I don't remember all of the MCs but there were 2 guys who were partners and did business together (their business included stuff like: killing, making ppl do stuff, etc.) One of them was tall and smart, and the other was shorter, really muscular, and tried to deal with most of the stuff with brute force. The brute force guy has a really rich fam, and I think at one point they meet an (assassin I think) woman who really loves the muscular guy. The manga was really dark and brutal buy I really liked it.
I know that my explanation was really bad, but please help me!!