Ninja Gangsters IV: The Mysterious Golden Castle(1983)

On their way to the Owari, Sanzo and Yumenogosuke gets lost in the Kiso Mountains. There they encounter a hidden gold mine being demolished by the Mino Naegi clan. The two join a beautiful girl named Tsubakuro Osen, whom they meet in the mountains to extort the Nabeki clan. They reach an agreement with Kageyama Taito to receive 300 ryo in three days but suddenly the Naeki clan is stripped of its power by the authorities... a plot set in motion by Sakai Wakasamori and Saegusa Kanmotsu.