1girl absurdres balloon blue_eyes blush breasts earrings floating_hair grey_hair grin heart_balloon highres idolmaster idolmaster_shiny_colors jewelry looking_at_viewer medium_breasts namiki_illust navel serizawa_asahi sideboob simple_background smile solo sports_bra star_(symbol) star_earrings stomach sweatdrop upper_body white_background white_sports_bra