1girl, bikini, black_bikini, blue_background, blue_eyes, blue_hair, breasts, closed_mouth, gokou_ruri, gradient_background, happy_birthday, long_hair, looking_at_viewer, meow_(nekodenki), mole, mole_under_eye, ore_no_imouto_ga_konna_ni_kawaii_wake_ga_nai, side-tie_bikini_bottom, small_breasts, solo, swimsuit