Nanako-san Teki na Nichijou RE - Vol. 1 Ch. 11 - Nanako Behind Glass

[MangaDex]

 

[Loopy-Loon]

Page 4 explains how Kawara manages to survive the multitudinous injuries he sustains, he's made of play doh, meanwhile Nanako must be a robot to break a window with her bare butt without even a scratch, would explain why she's still so naïve.

 

[Simpleton]

@Loopy-Loon I can only agree with the first assessment. The second one seems likely, although it could also be the blessing of idiots.