LOSE THE PLOT
One common criticism amongst the majority of Ninja Gaiden 3's reviews so far has been the story, or rather how moronic it is. The idea the developers had was to try and humanise Ryu Hayabusa a tad more, it clearly worked all that well. Do you know why? Because Ninja's are basically super-humans.
Aside from the pure-cheese world domination stuff, there's also something about Ryu seeking redemption from the thousands of previously murdered victims by murdering thousands more. They clearly didn't think it through.
Don't get us wrong, we enjoy a good old cheese fest every now and then, but what we're trying to say is the story doesn't have to make sense, and there doesn't even have to be any sort of plot to begin with. Who plays Ninja Gaiden for the plot anyway? Team Ninja instead should focus on making a game that is a power-trip for the player, not a cringefest.
Here's our plot for Ninja Gaiden 4: Some evil pirates kill Ryu's nin-dog, he totally flips out and goes to around the world killing bad guys. Also, there's a boss fight against a giant robot-dinosaur that fires lasers. Done, ship it.