I assume much of this story is fictional, though it is true that in the 16th century some Japanese did go to Europe and were welcomed. As for the important figures in the story, such as Lord Ieyasu Tokugawa, he is one of the most important figures in Japanese history...establishing the dynasty that ruled Japan for well over two centuries. So, while some is clearly true, don't take this as a history lesson.
Lord Ieyasu is having difficulties because his enemy is very well armed with European guns. So, he sends his rather impetuous (and occasionally stupid) son and his trusted retainers to Spain to secure guns. However, there is LOTS of intrigue and betrayals...and somehow the party ends up being captured by Moroccan pirates as they returned home to Japan. What's next? See the film.
I do wish that the introduction had been longer and had gone over this time period in Japan a bit more in depth. I am certainly no expert on this but I realized some important details were missing and should have been clarified. Still, even with this abbreviated introduction, the story was still very compelling and interesting. In fact, it made for a nice little adventure tale and kept my interest throughout...even if much of it seemed pretty farfetched. Also, pay attention to the music...it's really good.
By the way, did you notice that Spanish mega-gun never seemed to need reloading?
