Keyboard Crusher
From NND Medley Wiki
Keyboard Crusher refers to a German boy (then 14 years old) who destroyed keyboards in anger.
His real name is Leopold Norman (more on that later). He is also known by the abbreviations KBC, Kibokura, Kikura, Crusher, etc.
He is not the same child who appeared in the Gates series during his childhood. (Just to be clear.)
More information about Keyboard Crusher
See Japanese Keyboard Crusher wiki: https://w.atwiki.jp/bananathinking/