There really was a Yasuke, a man of African descent who served as a samurai under Oda Nobunaga. Yasuke, the anime, takes the general details of his life and backends them into a fantasy adventure story of roughly the same outlandish flavor as projects like Ninja Scroll. It's a prime example of how influences in international popular culture are and have always been cyclical and cross-pollinating: the story's by LeSean Thomas and Flying Lotus (who also provide the sensational soundtrack), and the visualization by animation studio MAPPA. What's frustrating is how its willingness to be over the top works against many of the other things about it that are just as special, if not more.
In a little village somewhere in Japan, the black boatman known only as "Yassan" (Lakeith Stanfield, far better here than in Death Note) ferries people back and forth, his face half-hidden behind an avalanche of dreads and beard. When he doesn't work, he drinks, and when he's not doing either of those, he sleeps and has nightmares of his former life. He was an African slave, whom Jesuit missionaries brought to Japan, and who came to the attention of Oda Nobunaga as that man was ramping up his ambitions to conquer the country.
Not all on Nobunaga's employ look askance at "Yasuke", as he is called. Natsumaru, one of Nobunaga's assembly of female samurai, feels kinship for Yasuke. She knows what it's like to be an outsider among insiders, especially when there is more to her than anyone else knows. Yasuke mourns her loss as keenly as his master's death, when the forces of the "Dark General" storm Nobunaga's castle and Nobunaga opts for suicide over disgrace. It's Yasuke who takes his master's head, and who escapes into the night rather than follow his master in death.
The alcoholic threnody of Yasuke's second life is punctuated when he's tasked with what looks like a simple mission. Saki, the sickly daughter of the singer who works at the bar where Yasuke drowns his sorrows, needs to go upriver to a special doctor. It's not because Saki's ill, though; it's because she's in the first stages of manifesting a supernatural power that all sorts of bad folks want to get their hands on. And so Yasuke, armed with his old sword and his smart mouth, heads upriver with Saki against an array of progressively more powerful supernatural villain-grotesques.
The unreal story
It feels almost unfair to say I have a problem with a project this inspired and electric. The construction of the whole — mainly the way it delves heavily into the fantastic — telegraphs the conceit that Yasuke's story by itself (even in a fictionalized form) wouldn't have been interesting enough by itself to its target audience. And so, to that end, the creators cluttered it up with mecha and magic and other things that feel superfluous and distracting, because they don't really touch on the story's central issue of being an outsider. By the time we get into stuff involving Saki being attacked on the astral plane by a nigh-immortal warlord, I felt like the show had lost its way. Why ditch out progressively on the genuinely interesting parts of this premise for a bunch of fantasy hoo-hah that could have been phoned in from any dozen other shows?
It's doubly disappointing given how good much of the material is with Yasuke and those who come to know him, in both his past and present life. They put the lie to how this story needed to be jazzed up to be worth telling. Such things matter when dealing with material whose core fascination is its historical roots. I don't know if the more over-the-top elements were added as part of the requirements to get it financed, or were intended to be there from the start (a sign that you can love your influences a little too much, I think), but the net effect is the same. It also indicates an unwillingness to fully own creative decisions: If you're going to give us a world where the Mongol armies won because they had power armor, at least adjust everything else to match, too?
None of this should deter anyone from watching Yasuke. Its technical qualities are unmatched, and it is never less than entertaining. But I still feel like the folks behind it hedged their bets, and as a result the project ended up missing its own point. I cam image a scene where they pitched the core idea to a producer, who replied, "A story about a black samurai? Great! But we need more giant robots and mutants." Oof.