What is "martial arts?"
"Martial arts" is the technique of fighting to enemies in past era, and a sport today.
For example, Karate is Japanese martial arts, and "Wushu" is Chinese martial arts. The fencing is European martial arts.
The Asian martial arts are mixed up or confused in Hollywood films.
Japanese soldier known as "Samurai" never used Wushu, but has used Chinese fencing in the films. Japanese fencing and Chinese one are completely different. Ninja never used kung-fu, but has done in the film.
Since a lot of Wushu actors and directors have come to the Hollywood, Wushu is no longer mixed up or confused with Japanese martial arts like Karate. But most Hollywood professionals still don't understand the Japanese martial arts.
Samurai didn't know about Karate until 120 years ago. Karate was introduced to Okinawa by the Chinese martial artists a long time ago, and it had been improved by Okinawa people until Japan, Edo administration, occupied Okinawa. So, Samurai shouldn't have known Karate until then.
And samurai's martial arts focused on fencing. There were lots of factions of Japanese fencing in Edo era. They fought to their enemies with swords instead of their fists. Jujutsu (different form today's Judo) or Sumo ( not today's Sumo) were used if necessary, but most fighting were taken place by fencing because samurais must have carried their sword when they walked in the street.
Ninja was spy organizations at Warring States Period in Japan. Their techniques is very similar to the special forces' one in the US or UK. How to sneak into the enemy's building or how to escape from the crisis was the main techniques. Since they were the spy, they had some special weapon like smoke bomb, chain sword, dirks and some tools to escape. They should have some techniques to fight to the enemies with sword or fists, but we don't know much about it because Ninja was forced to vanish after Edo era. Some descendants say that they have received the techniques, but there are no evidences. We don't know if they are true descendants.
A certain thing is that they did not use either the Karate or kung-fu.
If you wanna learn about the technique of Ninja, you better join the Army and enter the special forces such as Delta Force or SEALs or SAS rather than going to Ninja schools.
This is the fact of Japanese martial arts. Even if there are lots of samurai kung-fu films in the US, I'd like you to know the true Japanese martial arts, and I'm looking forward to being understood in the Hollywood film industry.
Now, I'm planning to write a spec script about samurai actors going to the Hollywood. It's gonna be a love romance. If you're interested in it, please let me know. I'll show you the script. The script will be completed by early October.