1girl, all_fours, ass, barefoot, black_hair, blue_one-piece_swimsuit, blush, brown_eyes, covered_navel, feet, foot_focus, foreshortening, from_behind, long_hair, looking_at_viewer, looking_back, matsunaga_kouyou, nose_blush, one-piece_swimsuit, original, soles, solo, swept_bangs, swimsuit, toes