Mio is Azusa's big sister figure in the anime. As for Yui and Ritsu, I don't really know anything other than I saw them asleep holding hands while rewatching the last few episodes.

Who were holding hands?

Yui and Ritsu

Oh okay

When?

Which episode?

Almost the final ep.

Okay. I’ll look. Maybe when they’re at Sawa-chan’s house?

No I think it was right after a show

Thanks