Why would you want to rip manga cover off?

Her eyes.

@voyager2d I think she means the plastic wrap(which is technically a cover)

Over the course of Vol. 3, there's been a definite increase in kawaii Nagatoro faces versus the twisted grin, crazy eye faces from the early chapters. Example - panel 2.

Nagatoro is strong as hell to tear such book apart. That's why he can't make a move against her actions