Great movie but...
Although your art style is really great and i love the visuals, there are a few things that really, really bug me about this movie. The first is the pacing. You keep alternating between fast shots and slow shots. You can't afford to have a 5 second long shot of a sword just falling through the air int he middle of a really fast-paced fight scene. That's one of the things i believe you need work on. There are other instances but i'm sure you could find them yourself.
Now the biggest point though is that i've always had a gripe with the "superhuman capable of doing anything and is ulitmately better than anyone else" thing. I mean sure the ninja can be talented, doesn't mean he has to completely own every single enemy he encounters. I mean sure you made him get hit like what, 2-3 times from the white fox and 2-3 energy balls from the red pig? You have to make it more dramatic, dare i say a bit more realistic so your hero doesn't seem like this insanely quick and invulnerable killing machine.
I suggest for example, when he kills the first three guards he encounters. He could've just thrown 2 ninja stars and them, hide somewhere and kill the third while he was looking at what happened. It may not be as "exciting" as what you did but seeing a ninja move at the speed of light and killing everything with just a single blow gets kind of dull after a minute. As for the white fox, he clearly should've posed a bigger threat to the ninja. The only thing he managed to do was make him lose his sword. I don't even think he hit him at all.
I hope you see what i mean when i criticize your mistakes but i really think that your movie still needs a bit of work if you want to make it more compelling. Anyway, that's it for my long review, hope you read it... Ciao!