4girls, blush, cushion, idolmaster, idolmaster_cinderella_girls, idolmaster_cinderella_girls_starlight_stage, idolmaster_cinderella_girls_u149, indoors, koga_koharu, lens_flare, looking_at_viewer, mat, matoba_risa, multiple_girls, on_floor, sakurai_momoka, sasaki_chie, sitting, sketchbook, wooden_floor