junior bra; training bra
A bra designed for preteens or young teenagers, often without underwire and with light support. The term is a wasei-eigo construction from 'junior' + 'bra'.
娘が初めてのジュニアブラを買いに行った。
My daughter went to buy her first junior bra.
Variant with interpunct; less common in everyday writing.
Wasei-eigo (Japanese-made English) from 'junior' + 'bra'.