1girl, blonde_hair, blue_one-piece_swimsuit, breasts, hair_bun, idolmaster, idolmaster_million_live!, kotori_ryou, medium_breasts, off_shoulder, old_school_swimsuit, one-piece_swimsuit, outstretched_arms, pool, red_eyes, school_swimsuit, sidelocks, single_hair_bun, smile, solo, spread_arms, swimsuit, tenkubashi_tomoka