(warning: good advice in post, not suitable for one handed internet surfers...)
waf dude,
Why are you hating on your friend man? If he picked up the hot one and you got stuck with the average then that is the way the cards are falling, I'm assuming he did the approaching since he ended up with the hot one anyway (if you approached and got tooled over to get an ugly girl then you need to lay down the rules!), it is your DUTY to cover your mans back smh. If he wants to go out on a double (which btw most fobs do because their English is bad so they like to bring along their best friend to chat in XXX...even if you yourself are solo (<-field tested experience)) then it is your duty to attend!
There are two ways in which to proceed depending if you want to fuck her or not (btw in my experience koreans are generally down for casual sex so I'd advise going for it...however if they all live together, as most koreans do, then the sex logistics will be tough to pull off unless you have a mate that can lend you a place, as I'm assuming you are still at home..)
trying to fuck her: physical contact initially, after a certain point you need to seperate the two girls so you can go do your thing (kissing/make out etc.) and he can do his thing...
not trying to fuck her: same as above except no touching on your part...and if she thinks you are just like a typical korean boy (i.e. typical boy) just 'playing it safe'..just don't respond to any of her communications unless it is to get your mate sex..or a threesome!
If you wish to discuss it further PM me