A somewhat literary or medical term for a girl's arrival at puberty. Often contrasted with 思春期 (adolescence in general).
See also: 思春期 (ししゅんき) · 破瓜
She reached puberty and experienced changes both mentally and physically.
Borrowed from Chinese 破瓜, an expression for a girl aged sixteen. The character 瓜 was understood as divisible into two 八 “eights,” yielding sixteen.