Nanako-san Teki na Nichijou RE - Vol. 1 Ch. 22.2 - Nanako In The Clubroom

[MangaDex]

 

[Simpleton]

Rather than "shaved" it's more likely she's "bare" (implication of hairless being that she's childish, but reality being that puberty sets out differently for all, and for her it very clearly went with a boobs first approach).