Since I'm trying to expand from just line sketches to sketches with a bit of gradation, I also purchased the Sakurai Koi Coloring Brush Set in Grayscale. I'm still scared of color, but this set offers 3 gradations of warm and cool grays, so it's a good stepping stone to learning to sketch in values. This set is unequivocally the best buy so far, and I absolutely love using them. Their best feature is that if they're applied lightly, they don't bleed through the paper of my monologue sketchbooks, which is very important to me since I always use both sides of the paper. Once I'm comfortable with grayscale I think I'll eventually move up to buying their colored set. Below are some of the sketches I've made with this combination of tools.
First Sketches, people in Starbucks
Woman in Greenbelt 1
Dimsum Chefs in Shi Lin