4girls, =_=, air_bubble, asakura_toru, barefoot, blue_one-piece_swimsuit, blush, breasts, bubble, chain-link_fence, cleavage, closed_eyes, day, dutch_angle, feet, fence, forehead, fukumaru_koito, goggles, goggles_on_eyes, hair_bun, higuchi_madoka, holding_breath, ichikawa_hinana, idolmaster, idolmaster_shiny_colors, medium_breasts, multiple_girls, noctchill_(idolmaster), one-piece_swimsuit, outdoors, parted_bangs, partially_submerged, partially_underwater_shot, pool, pool_ladder, school_swimsuit, single_hair_bun, soles, splashing, submerged, swimming, swimsuit, toes, water