I can't get passed those black ninjas. I keep dieing and I can't find any other place to save and I don't have any health potions either what do I do?

Black Ninja's are a bitch, especially on hard mode. I would suggest that you just run past them and try to avoid their incendiary shurikens. You should use a combination of jumps and rolls to make yourself a harder target to hit. You could buy some elixirs from Muramasa in the clock tower square.

To get to the nearest save point go into great bridge square and follow it around to the left. There is a small alley by a fence. Wall jump between the walls and then jump from platform to platform and you will find yourself on a balcony above Muramasa's shop. Turn the lever to unlock the door to pleasure street. At the end of this street is a save point.

Hope this helped!

Or kill em just block their combo's and then do one of ure own they give quite a number of yellow essence

Stay close, but don't let them surround you.
Always jump after a roll to cancel the short pause at the end of the roll.
Block until you see an opening.
Use counters, wall jumps and the Izuna Drop.

If you're in real trouble (i.e.: your health is low and there are 3-4 shurikens in your skin and they're about to explode), you can save yourself by using magic. If the blast occurs while you're using ninpo you won't get hurt.

roll, jump,
and most importantly counter
and i'd say using ninpo alot helps, too

quote

Use counters, wall jumps and the Izuna Drop.