2girls, ball, beachball, bikini, black_bikini, breasts, frilled_bikini, frills, from_below, higuchi_madoka, idolmaster, idolmaster_shiny_colors, in_the_face, inumantle, looking_at_another, mayuzumi_fuyuko, medium_breasts, multiple_girls, navel, outdoors, splashing, swimsuit, wading, water, water_drop