Secret of Ninja (1985)

Secret of Ninja 1985 / 洪門鬥惡者 1985 / Hong Men Jue E Zhe , Ninja vs. Mafia , Mafia vs. Ninja , 洪門闘忍者 , Mafie Versus Ninja , Hongmen Dou Ninja

Sewage workers Jack and Charlie get involved in an international Asian gang war when Jack helps the boss of a Shanghai gang against one of his rebellious underlings. This underling then strikes a deal with the Japanese Yakuza in the hopes of toppling his boss and become the leader of Shanghai himself. When the Yakuza assassinate the Shanghai boss, Jack pledges to avenge his new friend's death. As he seeks out those ultimately responsible, he does battle with a variety of ninjas and mercenaries from around the world. (Source: IMDB by JMR)