Oh my gosh this is amazing! Doku is by far the best and coolest villain ever, and this is a fantastic rendition of him! I quite like the purple qhost stuff pouring out of his faceplate (very similar to how it did that in the game). I kinda want to play Ninja Gaiden again just to play against him.
Doku was perhaps the toughest video game boss, ever. In fact, I never beat him in.... I borrowed my brother's Ninja Gaiden and just never quite could get it finished. I finished the later games in the series but Doku stands as a testament to how Japanese games are not for the weak!
Hey, I never thought I'd see you revisit any Ninja Gaiden art. The skull silhouette in his fire-face looks a lot more interesting than his samurai faceguard. I always liked how he looked without that thing and I think this would have looked really cool if it had been in the games.
Personally, though, I always thought Doku was a douche, but to each his own.