Yano was mad because she only felt ease in her own "glass tower", because she was too accustomed to the loneliness where no people really cared about her feelings and no one who was close enough for her to truly care about at all. When Utsumi reached to her, she felt unease due to the unfamiliar...
Just finished reading this last chapter, thanks for the translation.
The story is quite complete and has it ended here is appropriate in my opinion, as it's based on Manio sensei's personal experience. Unlike Kitakawa, Aishita is more or less an "I-manga", therefore, it's hard to be as dramatic...
We haven't seen what the other two are doing yet, and they can have as many meat-shields as they want in a town full of normal people. Ginko might eventually be the one who can't go all out when innocent citizens are involved, or so they might have planned.
@ShinduPK4 If I remember correctly, there's a similar scene in Donnie Yen's movie Flash Point (or Kill Zone). As Gunlord500 said, Giambi is not trying to tackle Heimbritz as he knows that Heimbritz is strong enough to hold the ground, so he uses the momentum to move to Heimbritz's back to choke him.