Are there really ninjas these days?
I don't know that anyone can claim lineage to those shadowy warriors of the past, let alone claim to be one of them.
Ninjutsu schools apparently still thrive. Even if their claim to lineage is true, I believe they do not, at least as far as what can be publicly learnt, replicate training necessary to be an extremely hard man the way they did before in feudal Japan - I believe the equivalent level of training would be like what the SAS boys do. There are many reasons for this, of course, many practical reasons (safety, time and 'real life' etc).
However, I concede the training a terror cell in the middle east may well be just as intense as what our best soldiers go through albeit lacking maybe in finesse. Perhaps they have nothing else to do, perhaps they are motivated by other concerns and are less concerned about safety.
The upshot is, if one considers oneself "hard as" and completely imba as some do, please remember, knowing the 'apparent theory' of how to do something isn't the same as having done the equivalent things, in a more practical manner, a million times over in real conditions under pressure especially when one's life depends on it, for real.