1girl, arknights, armpits, bikini, black_bikini, breasts, criss-cross_halter, day, detached_sleeves, halterneck, horns, long_hair, long_sleeves, looking_at_viewer, navel, official_alternate_costume, outdoors, ponytail, purple_eyes, red_hair, solo, surtr_(arknights), surtr_(colorful_wonderland)_(arknights), swimsuit, thigh_bow, thigh_strap, three_twosix, tying, very_long_hair