If you want a way better samurai show to watch, I HIGHLY recommend Rurouni Kenshin, available to watch in Crunchyroll (better version, original) or Hulu or HBO (voices changed for some characters from the original)
It takes place in the late 1870s during the Meiji era. Historical events are accurate and it is realistic.
Yasuke was poorly written, rushed, boring. No explanation as to why there are futuristic robots in ancient Japan. The main purpose of the show is to show off the main characters no matter if they throw random magical creatures without explanation to them.