The daimyo Oda Nobunaga personally gave the titular hero a pair of swords to promote him to the rank of samurai, the first time a non-Japanese person had ever been honored this way -- something the anime highlights. However, numerous characters in the series insult Yasuke by calling him a "servant," which demonstrates a major misunderstanding of the nature of samurai in Sengoku Era Japan.
The samurai have been so mythologized that it is often difficult to separate fact from fiction. Samurai were a hereditary caste of noble warriors, dedicated to serving regional lords called daimyo. By the 16th Century, they had embraced an honor code known as bushido. They were also legally permitted to kill any peasant who did not show due respect, demonstrating their high status. The word samurai literally means "servant," signifying their service to a feudal lord, though many preferred the term "bushi," meaning "warrior." Most samurai were born into the caste, but during the Sengoku Era, it was not unusual for commoners to be promoted to the ranks of the samurai. In some instances, a low-ranking samurai could even become a daimyo.
Oda Nobunaga, the daimyo who made Yasuke a samurai, was the most powerful man in Japan. Upon his death, he was replaced by Hideyoshi Toyotomi, a man who began his career as Nobunaga's sandal-bearer but was continually promoted for his accomplishments until he eventually inherited all of the territories that Nobunaga had conquered. This demonstrates that service to a lord was a core part of the samurai ethos and that anyone could become a samurai through such service. As such, it makes little sense to hear characters in the Netflix series repeatedly insist Yasuke cannot be a samurai since he was once a servant.
The first time Yasuke meets a samurai in the anime, he intervenes when the warrior tries to kill an unarmed boy. This unnamed bushi then tries to cut down Yasuke for being a servant who dared speak so directly to a samurai. Yasuke trounces him, which brings him to Nobunaga's attention. Later, he joins Nobunaga's assault on the Iga Clan, where Yasuke is derisively called both "slave" and "servant," which enemies and allies use to justify their beliefs that he cannot be a samurai. He kills the Iga commander in single combat, thereby proving his worth. At the victory celebration, Nobunaga personally leads a toast to honor Yasuke's accomplishments. But even then, one of the daimyo's generals, Mitsuhide, tells the Black samurai "servants will always be servants." Comments like this are repeated throughout the show, despite the fact that the samurai were servants.
It would be a mistake to suggest that all samurai had the same attitude about their role in society. Because most were born into their high-status position, many of them jealously guarded against what they saw as a usurpation of the traditions that made them special. However, Japan was a feudal society based on service, where peasants and samurai served their daimyo who in turn served the shogun and emperor. It was specifically because Yasuke distinguished himself as Nobunaga's servant that he proved worthy of becoming a samurai. Anyone who dismissed the importance of such loyal service would be demonstrating a most un-samurai-like attitude.
