1girl, arknights, arms_up, bikini, black_bikini, black_ribbon, breasts, cleavage, closed_mouth, cloud, cowboy_shot, criss-cross_halter, detached_sleeves, evening, hair_ornament, halterneck, hands_in_hair, horns, large_breasts, long_hair, long_sleeves, looking_at_viewer, navel, official_alternate_costume, purple_eyes, red_hair, ribbon, riel_(ataraxia2334), side-tie_bikini_bottom, solo, star_(symbol), star_hair_ornament, stomach, sunset, surtr_(arknights), surtr_(colorful_wonderland)_(arknights), swimsuit, swimsuit_cover-up, very_long_hair