Poly stuff is so rare that whenever I see it it's like a part of my psyche has been edging for a looong time, and it's just one big release of oxytocin.
This game is ultimate yuri game in fact. PLUS version reveals it all. Just notice that fragile, calm peace and love achieved between girls, and all was ruined when YOU, yes, you, male, joined the club. Males are pure evil.
For anyone who doesn't/haven't read the manga, in the newest chapter Asuka tried a new make up on Tomoko which actually made Tomoko looks nice (see above) so yes that's her.