[There is absolutely nothing Kanda could be doing in the library, but the explosion is pretty massive. So he can spot it from wherever he's walking by at, and so he stares at the messy figure that emerges from it and then proceeds to have a fit.]

[Lolwut. He's going to step closer and give the guy a very dry look. You gotta be shitting him. Seriously.]

You call that 'mastering'?