I love how awkward it's Mimi with the whole situation. As an inmortal that has seen probably thousands of people die, yet at sight of the death of her friend she doesn't know how to properly react. She can't feel openly sad, nor it doesn't hit her that she won't see her friend again after she's dead until the funeral. So, the proposition in this chapter comes from a very interesting place in Mimi's psyche.
PD: By the way, it seems that if you kiss in front of Shiina and Mimi you are fucking dead. Like that senpai on the first episodes KEKW.
Now I'm double the sad.