Ninja Assassin is a perfectly competent movie if you can successfully squint and ignore the whole “secret clan of ninjas operating covertly in the modern world” premise. But I know that isn’t what you really want to know. The answer to your question is: yes.
Yes, there is an assassin who is also a ninja.
Yes, there are people attempting to kill our protagonist, knowing he is a ninja.
The movie features ninja assassins and also ninja assassins.
There is even a ninja assignation in the backstory.
Ninja assassin assignation.
Which resulted in death.
Ninja assassin assignation assassination.
If we consider the secret clan of ninjas as a nation, you might say there was a
ninja nation assassin assignation assassination.
But you shouldn’t, because that would be inaccurate.