1girl, armpits, beach, bikini, blue_bikini, breasts, brown_eyes, brown_hair, cleavage, closed_mouth, collarbone, day, idolmaster, idolmaster_cinderella_girls, idolmaster_cinderella_girls_starlight_stage, long_hair, looking_at_viewer, lying, ocean, on_back, sawada_marina, sawarakajin, short_hair, sideboob, smile, solo, surfboard, swimsuit, v, wet