I have liked Riko x You since that one doujuin where they were trapped in a locker together and You couldn't move at all without grinding her knee into Riko's crotch. Hilarity ensued.
^^Mm... I don't know about that one. Umi's more reserved and respectful, because that's how she was raised. I don't necessarily think she has a problem that part of herself.
Maki just has a standoffish air about her. And puts up a barrier that makes it hard for people approach her, but really she's just shy and not used to interacting with others. When people do try she begins to loosen up a bit.
It's all a front, my gender-appropriate sibling. Deep beneath Umi's uptight exterior beats the heart of a freak just waiting for someone to give her permission to let it loose.