1girl, o, ass, ass_support, b1ack_illust, bikini, blue_bikini, blue_hair, blush, breasts, butt_crack, dimples_of_venus, halterneck, hands_on_own_ass, idolmaster, idolmaster_(classic), idolmaster_million_live!, kisaragi_chihaya, looking_at_viewer, looking_back, shoulder_blades, simple_background, skindentation, small_breasts, solo, string_bikini, swimsuit, white_background