1girl, arknights, ass, back, bare_shoulders, bikini, blue_sky, breasts, day, detached_sleeves, from_behind, hair_ornament, hair_rings, halterneck, horn_ornament, horns, long_hair, long_sleeves, looking_at_viewer, looking_back, lufi_ays, mouth_hold, official_alternate_costume, palm_leaf, purple_eyes, red_hair, sideways_glance, sky, solo, star_(symbol), star_hair_ornament, surtr_(arknights), surtr_(colorful_wonderland)_(arknights), swimsuit, thigh_strap, very_long_hair, white_sleeves