1girl, armband, ass, black_eyes, black_hair, blue_background, blush, from_behind, glasses, hair_ornament, hairpin, hand_on_own_hip, holding, idolmaster, idolmaster_cinderella_girls, idolmaster_cinderella_girls_starlight_stage, looking_at_viewer, looking_back, one-piece_swimsuit, open_mouth, saejima_kiyomi, school_swimsuit, short_hair, shy, simple_background, solo, standing, sweatdrop, swimsuit, wavy_mouth, whistle, yama_tatsuo