Well everyone is hating on Akira I kinda fell bad for her.
I think Akira might have some feelings for Mayuki maybe like above friendship but not quite love my best description would be like a little sister especially after I read page 4-5 she was in denial that it could be Mayuki since she had good relationship with her.
She might have dated Mayuki eventually if she had not met Rin and fell in love with her.
After she met Rin and had much less interaction with Mayuki because of different school and much more interaction with Rin she slowly fell more in love with Rin and her relationship with Mayuki was kinda stagnated.
When she first learned that Rin kissed someone she was just annoyed but after thinking that it might be Mayuki her state was obviously much worse.
When she saw that it was Mayuki that Rin kissed and Mayuki's expression of happiness on page 19 she was in an extremely bad mood on page 21.
But when she learned that Rin was kinda hopelessly in love with Mayuki her good feelings for Mayuki was heavily distorted since she always saw her kinda like a little sister so maybe after she calms down a little her thought might not be so contemptuous.
Here's all my thoughts. My first language is not english so it might be a little hard to read and understand