![1boy 1girl absurdres ascot back_bow barefoot black_hair black_ribbon blazer blush boots bow bowtie bra breasts brooch brown_hair business_suit coat collarbone collared_shirt commentary_request covering covering_crotch cross-laced_clothes dress earrings eyebrows_visible_through_hair formal frilled_dress frills full_body gloves hair_between_eyes hair_bow hair_ornament hairband high_heel_boots high_heels highres idolmaster idolmaster_cinderella_girls idolmaster_cinderella_girls_starlight_stage jacket jewelry kirin_kakeru long_sleeves navel neckerchief necklace necktie nipples no_penis no_shoes nude panties pantyhose pleated_skirt puffy_short_sleeves puffy_sleeves purple_eyes ribbon sailor_collar school_uniform shiragiku_hotaru shirt shoes short_hair short_sleeves simple_background skirt small_breasts smile suit suitcase sweater training_bra underbust underwear underwear_only variations white_background wrist_bow rating:q score:7 post #3342804](/cdn_image/preview/dd/84/dd8495b7736552ed9bb358863a13f931.jpg)
A cupless bra similar to a sports bra but worn exclusively by young, developing girls. The training bra is intended to help young girls become comfortable with the idea of wearing lingerie.
Also known as "trainer bra" or "bralette".
http://en.wikipedia.org/wiki/Training_bra
This tag implicates bra (learn more).