deyui, kisaki (blue archive), kisaki (swimsuit) (blue archive), blue archive, character request, highres, 3girls, ass, bikini, black bikini, black hair, blue sky, braid, butterfly hair ornament, cloud, day, flat chest, from behind, hair ornament, halterneck, long hair, looking at viewer, looking back, messy hair, missing halo, multi-strapped bikini bottom, multiple girls, ocean, official alternate costume, official alternate hairstyle, open mouth, outdoors, side braid, sky, slap mark, solo focus, spanked, swimsuit, wading, wet