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.