Ai Kora/Ho Yay

Ai Kora has Haiji, a bisexual Love Freak pretty-boy who loves the "parts-loving" protagonist, Maeda, because he thinks he has a pure heart. Maeda goes on to discover Haiji has what he considers an ideal butt, and for the rest of the series has to remind himself that said butt is on a guy...
We've also got Kureha, a Schoolgirl Lesbians with a glasses fetish who quickly becomes friends with a cheerfully-oblivious Yukari. Kureha proceeds to gush over Yukari in nearly every one of her appearances.