Roku was a half-demon from Horai Island, and is Dai's twin brother. He appears in the fourth InuYasha movie. Roku is also Asagi`s love interest.
As young children, Roku and Dai survived the Four War Gods attack on the island and received the Mark of the Four War Gods to prevent them escaping. They were destined to be used as fodder for the War Gods' own purposes until Inuyasha's group saved them and the other half-demon children. At the end of the film, he sets out with the other remaining half-demon children to live in the outside world.
Both Roku and his twin often annoy Inuyasha by telling him he will be unable to defeat the Four War Gods. Though they have annoyed the others at times as well. They are both very immature and have smart mouths, making witty and unnecessary comments at times.
Roku and Dai are both nearly identical in looks. They are both tanned and have sharp, defined features. They have orange eyes and pointed ears (showing they are both half-demon). The way to tell him apart from Dai, is that Roku's hair is mostly green, and his outfit is a lighter shade of blue.
Roku wears a light blue tunic with rope tied around the waist. He is barefoot all the time, like the other half-demon children.