Trying to find a doujin

Hi Guys,

I am looking to find a doujin where a university student went with her friend to visit their tribe land. The tribe had sex in public and they made her drink something that she got totally hocked.

let me know if i need to be more specific :D

I think I've read this one before. I remember it being about street fighter, the character that was part of a tribe was Elena. Her friend went with her and the tribe had sex in public, the friend had flat chest, or small at least iirc. I couldn't find it, but I hope it helps.

Edit: Found it. Riko's Big Adventure by Mikami Cannon.

OMG, YOU ARE MY HERO!! THANK YOU.

No problem, I also took the chance to add it to my collection hahaha