1girl, artist_name, ass, back, barefoot, bikini, black-framed_eyewear, blue_eyes, blue_sky, breasts, cloud, cloudy_sky, dated, day, from_behind, girls_und_panzer, glasses, grey_hair, halterneck, kneeling, looking_at_viewer, looking_back, matsui_yasutsugu, medium_breasts, open_mouth, outdoors, round_eyewear, rumi_(girls_und_panzer), short_hair, side-tie_bikini_bottom, signature, sky, smile, solo, swimsuit, thong_bikini