What is the cover of Reset! Chapter 2 a reference to?
Now I feel stupid...

A little thought and twenty minutes with Google image search has got me pretty sure that this cover is a reference to Kud Wafter:



Kud Wafter is the spinoff of Little Busters that continues the story of Kudryavka Noumi, in the same way that Tomoyo After continues the story of Tomoyo Sakagami from Clannad. I forgot the spinoffs existed, so I didn't look into them.

The Reset! character on the Chapter 2 cover uses the name "Kudryavka" as a nom de plume for her poetry, which makes it pretty near a sure thing.