sudachi (calendar), kousaka kirino, kousaka kyousuke, ore no imouto ga konna ni kawaii wake ga nai, highres, 1boy, 1girl, :d, aged down, aqua eyes, bare shoulders, black hair, blue eyes, blue hair, blush, brother and sister, brown hair, casual one-piece swimsuit, child, family bonding, frilled one-piece swimsuit, frills, hose, hug, male swimwear, one-piece swimsuit, one eye closed, open mouth, pool, short hair, siblings, sitting, skirt, smile, striped clothes, striped one-piece swimsuit, swim trunks, swimsuit, toy, wading pool, water, water gun, yellow male swimwear, yellow swim trunks