4girls, andou_shuki, bikini, blue_eyes, blush, braid, breasts, breasts_apart, brown_hair, character_name, collarbone, dated, hands_up, happy_birthday, highleg, highleg_bikini, idolmaster, idolmaster_million_live!, kousaka_umi, looking_at_viewer, lying, mat, medium_breasts, multi-strapped_bikini, multiple_girls, navel, on_back, outdoors, round_teeth, shade, smile, solo_focus, swimsuit, teeth