The group discovered that Yui is living on her own and so Kyouko decided to visit her on holiday. Hilarity ensues.
This episode is focused on Kyouko and Yui (at least the latter half) as we discover that they have known each other since like forever (including Akari) and how Chinatsu wants to join the group, too. For Yui-senpai, presumably. Hinted at the beginning of the whole event, turns out Kyouko cared about Yui after all and they proceeded to the bed at night in the end. IYKWIM.
A normal Yuru Yuri episode which is a good thing.