They have those in other countries. And they aren't always regarded as chivalrous and noble people.
It's more the mythical literary status of them here that is unique, sort of the American version of a knight or samurai.
I'm saying this mostly, Wolf, because there aren't any Japanese on RF who seem likely to chip in here. With that in mind, here are some things about Japan and Japanese culture that seem likely to interest you and a few other RFers....
It's possible to **** off certain Japanese people by calling their 'samurai' ancestors, 'samurai'. I've done it, possibly more than once. The correct term in those cases is 'bushi'. Basically, a more honorable name for 'warrior', and the root in the word, 'bushido' -- the way of the warrior. Came into usage more or less the same time as Zen entered the scene, and of course, both of those can be traced back to China.
The best warning sign is to avoid 'samurai' anytime you aren't sure of the status of someone's ancestors. It seems for families whose ancestors ranked high on the scale, 'samurai' is under certain circumstances an insulting word to begin with, let alone an outrageous demotion of their ancestors.
It's like telling Lee's descendants, Lee was no more consequential than any other private in the Army of Northern Virginia. If you told them than in a context that further hinted you thought he was also the lousiest private in the Army, then that's how bad calling the wrong person's ancestors 'samurai' can potentially come across to them as. But I think, if that were ever likely to happen, you'd best be America under National Guard protection anyway. I've only been told it can get that bad, I've never seen it.
To me, and I'm sure to some others, there are lot more fascinating things about Japan than that bit of trivia, but I'm guessing it's easier to come across those other things, than this one. I only know about it because I got in trouble for not knowing about it. Never once came across it in any university course, 'normal' personal conversation, or in any other way.
I think there's some chance this is like the 20 words for "I" in the Japanese language. Only about 5 of them are necessary for most Japanese to know in order to get through life, so most of the remaining 15 aren't known even in Japan by most Japanese people.
Please don't assume I'm an expert on Japan. I only know a little bit about a few aspects of the country.