Fluid is right
. The sumi/rice paper ones are so difficult becuase it's very hard to control the flor of the ink. The rice paper absorbs it instantly. So, if you hesitate, and hold the brush still for a sec, you get a blob. Very hard to make points, like for ears, since the ink wicks out evenly in all directions. So, one cannot really get detail, only "impressions". I rely on the view, who knows what a horse's eye really looks like, to fill in the detail with their mind.