1girl, ball, beachball, bikini, blonde_hair, blush, breasts, cleavage, feet, holding, holding_ball, holding_beachball, iicecall, long_hair, medium_breasts, navel, nogi_sonoko, ocean, open_mouth, outdoors, plaid, plaid_bikini, seiza, sitting, smile, solo, swimsuit, yuuki_yuuna_wa_yuusha_de_aru, yuusha_de_aru