1girl, bare_arms, bare_legs, black_one-piece_swimsuit, black_skirt, blue_eyes, braid, breasts, casual_one-piece_swimsuit, collarbone, grey_hair, head_tilt, idolmaster, idolmaster_shiny_colors, kusaka_io, looking_at_viewer, miniskirt, one-piece_swimsuit, pleated_skirt, pool_ladder, poolside, serizawa_asahi, sitting, skirt, small_breasts, solo, sparkle, swimsuit, swimsuit_skirt