So as a book, i'd say it was definitely a 5 - very enjoyable and easy to read. As a biography, it's more like a 2 - there is too much blending of fact and fancy.

I'd almost say it's a factual novel. It's written like a novel, but it's not fiction. 

It definitely gave me a good understanding of Japan in the late 1500s, and I felt immerses into Yasuke's life. I felt the "end" had too many loose threads that seemed indirectly linked together (which leads to the factual novel aspect of it).