1girl arms_up blue_sailor_collar blue_skirt brown_eyes brown_hair commentary expressionless long_hair lying navel neckerchief on_back original oto1_030 panties pleated_skirt red_neckerchief sailor_collar school_uniform serafuku shirt short_sleeves skirt solo stomach symbol-only_commentary underwear unworn_shirt unworn_skirt upper_body white_panties white_shirt