An additional pun:

The first box on the first page reads 追試勉強中　(tsuishi benkyouchuu). Tsuishi (追試) is a homophone for tsuishi (墜死) which means "falling to your death."

It's a good thing she hadn't called Mio

Evangeline_A.K._McDowell said:
An additional pun:

The first box on the first page reads 追試勉強中　(tsuishi benkyouchuu). Tsuishi (追試) is a homophone for tsuishi (墜死) which means "falling to your death."

Thank you for that, I got even more laughs