I want rin and mayuki end game... idk theyve already kissed and they are both comfortable w eachother, the basketball senpai seems a little clueless to her kouhai and rins feelings.. :/
Um... You understand what the "Polyamory" tag means, right?
And while Akira might be clueless about Mayuki's feelings (that she hasn't voiced yet), you can say the same thing about Rin's cluelessness about Akira's feelings (which she also hasn't voiced, for good reason).
Rin is very clearly a person who is poly to the core. She has ALWAYS had difficulty "picking favorites". When she loves people, she loves equally. She doesn't have the possessive, "I want them all to myself" type of feelings that Rin is currently feeling toward her and that her middle school kohai who slapped her in the face when Mayuki first met her felt.
It is unclear right now whether that is natural for Mayuki or not. She clearly has no problem kissing Rin and I would say that she most likely has started to harbor feelings for her, but I doubt that she realizes that. Her lack of self-confidence and inferiority complex in regards to Akira got in the way of her confession today, and that is probably for the better. Akira's "you have to be better than a pro basketball player for me to want to date you" mindset, at least when it comes to fellow athletes, would probably kick in with Mayuki, at least as an excuse. Either that or Akira would have told her that she liked someone else. But this outcome gives Rin and Mayuki's relationship more time to grow before Akira is involved, which will lead to Rin falling for her more than she already has.
The real question on the path to a poly ending here is Akira. How do we go from "I want her all to myself" to "I love both of these girls"? Is it as simple as RIn telling her that she loves them both and cannot choose and Akira, having heard her story about the girls in middle school, agreeing to give it a try and falling for her kohai? Or will Mayuki win Akira's heart only to realize that she also loves Rin, confess that to Akira after Akira tells Mayuki about her own feelings, and have Akira laugh and tell her that she, too, loves Rin, but she didn't think she would ever return her love so she was planning to move on? Then Mayuki, never one to give up easily, would hatch a plan to make Rin realize that it's alright to love them.
I can see many scenarios and I can't wait to see how things work out!