![1girl animated antenna_hair ass_visible_through_thighs bangs bare_arms bare_shoulders bike_shorts black_shorts blush bouncing_breasts breasts breath cleavage collarbone commentary_request cowboy_shot eyebrows_visible_through_hair eyes_visible_through_hair fight_ippatsu!_juuden-chan!! girly_running gym hand_up heavy_breathing indoors large_breasts looking_at_viewer medium_hair midriff_peek no_bra nori_tamago open_mouth parody pink_hair red_eyes running saigyouji_yuyuko shorts skindentation solo tank_top thigh_gap thighs touhou treadmill ugoira white_tank_top rating:s score:32 1girl animated antenna_hair ass_visible_through_thighs bangs bare_arms bare_shoulders bike_shorts black_shorts blush bouncing_breasts breasts breath cleavage collarbone commentary_request cowboy_shot eyebrows_visible_through_hair eyes_visible_through_hair fight_ippatsu!_juuden-chan!! girly_running gym hand_up heavy_breathing indoors large_breasts looking_at_viewer medium_hair midriff_peek no_bra nori_tamago open_mouth parody pink_hair red_eyes running saigyouji_yuyuko shorts skindentation solo tank_top thigh_gap thighs touhou treadmill ugoira white_tank_top](/cdn_image/preview/20/ab/20ab768f4bc52ccede0c3abc879aa059.jpg)
Refers to breasts in motion, often as part of a .gif or flash animation. If it is not an animation, something like a motion blur or movement lines must be present to convey a sense of movement.
If one breast is up and the other is down, add the unaligned breasts tag as well.
Example: post #694780.
This tag implicates breasts (learn more).