Hangaku belongs to the Jo clan (related to the Taira clan) which was a powerful local clan of Echigo Province, whose father was Sukekuni JO and whose siblings were Sukenaga JO and Sukemoto (Nagamochi) JO.
越後国の有力豪族である城氏(平氏)の一族で、父は城資国、兄弟に城資永、城助職（長茂）らがある。