Apparently there is a way to trigger a Nasir x Kol x Yoshiro Garcia threesome ending but I can't figure it out
It has been a long time since I played this but I believe you have to make moves on Kol as you normally would, then flirt with Nasir while doing the engineering course. Then at some point while having sex with Kol later you get the option to mention that you like Nasir too or something, then he sends you to his room to basically secude him and you end up with both of them.
**Big Spoilers, duh**
To unlock the threeway, do the obvious Kol route, but DON'T hook up with him. The main trigger is do NOT let Kol shower with you in the med bay after you both get shot. Shortly after that, Nasir will confront you (and Kol) in the kitchen and accuse you two of banging, and Kol will say, "We have haven't yet, but we're gonna." He can only say that if you haven't given in to temptation yet, so you gotta delay that gratification just a little bit to win the best ending. :)
Nasir will then ask you if you even want to bang Kol (save the game and answer "No" to unlock a GAME OVER ending with gallery artwork), but then reload and answer "Yes...but..." and the ultimate love story will just unfold from there. :) You're welcome!
I appreciate the effort of telling me. Hopefully it helps someone else who wanted to do that route. I just brute forced every option until I finally got it, I remember telling Kol no once and it didn't work, then i did it again on another playthrough and it worked, so earlier choices also matter. I just tried to play as submissive as possible.