Course Requirement

Naturally one of the things an aspiring hero must learn is escapology, for all the times some dastardly villain might capture said hero and imprison that hero in some diabolical death trap - - or just some out of the way closet for the unimaginative villain. 

As such, one of the required courses at the hero high school in My Hero Academia is "Escape Methods 100", where the heroes in training are taught through first hand practical experience what it feels like to be trussed up and how to extricate themselves from such a situation.  Such is the situation Momo Yaoyorozu and Mina Ashido find themselves in.

And Midnight is the "tough teacher".