COULDN'T POSSIBLY CONTAIN SPOILERS BECAUSE THAT WOULD SUGGEST I HAD SOME IDEA WHAT THE HELL WAS GOING ON
Zodiac America: The Super Masters? That's a bit of a surprise because it's marketed as Zombie Rivals: The Ninja Masters and is listed on the IMDb as Zombie Vs Ninja. Either way, it does have zombies AND ninjas but, crucially, no combat between the two.
It does have some sort of revenge plot in which villains kill the kindly village ginseng seller, and his son seeks justice. He becomes an apprentice to a neighbourhood undertaker with bad teeth and falls in love with a local girl, and seeks to develop his martial arts skills by carrying coffins full of rocks around. The undertaker also keeps raising the recently deceased as zombies so our hero can fight them. Meanwhile a wandering ninja, dressed in shiny yellow with a Ninja logo on his headband (just in case we thought he was a plumber or a behavioural psychologist or something), is repeatedly attacked by other colour-coded ninja assassins for no adequately explored reason. Neither plotline appears to have any bearing on the other, leading to the feeling that you're watching two separate but equally dull movies spliced randomly together.
It's directed (pseudonymously) by Godfrey Ho, something of a specialist in the quickie ninja genre if his IMDb entry is anything to go by - it lists no less than fifty three movies with the word Ninja in the title. Leopard Fist Ninja, Ninja Death Squad, Ninja Strike Force, Bionic Ninja: they're all his and frankly he's welcome to them. It's cheap and shoddy, it doesn't make much sense, the score appears to have been cobbled together from existing music, and the dubbing is absolutely atrocious even by the standards of Shaw Brothers knock-offs. All of which I could forgive, or at least accept, were it not for the fact that the movie is eye-wateringly dull. Not even close to worth watching, under any title, even for the cheapest of laughs.