Hakuhodo S100 series is just about as good as it gets. The beautiful makeup brushes with their orange-red handles are made of wonderfully soft uncut hair (S121G is blue squirrel, S133 is Canadian squirrel). The hair is tightly packed so the head has some serious heft while remaining sleek and thin for packing on color. These two brushes are ideal for use with high quality finely milled eye shadows and/or any soft textured shadows that tend to crumble when touched with too coarse a brush.
S121G is paddle-shaped and relatively large, though as you can see it's definitely not the biggest one out there. As you can see, Shu Uemura 13G is the closest one to Hakuhodo S121G, but there's a significant difference as the Shu is floppier while S121G is quite firm (well, as firm as the dreamily soft hair allows) and is better for serious loading of pigment. The size and hair quality also make the brush great for sheer washes of color and even blending in careful strokes. It's so useful and versatile I eventually bought a second one. This way I can use them with two contrasting colors in one application.
Hakuhodo S133 is smaller and can be used for lids and anywhere you want to cover less surface. I use it to blend two colors together, create gradation and soften edges when working with very fine textures. It's pretty interchangeable with another Hakuhodo brush, the Kokutan Eye Shadow Brush WM (E0186), but S131 is softer.
Both S133 and S121G are such amazing performers because they allow for very clean application. They place the product and blend it without messing anything up, erasing or smudging. They look like luxury brushes, but like all Hakuhodo products they are items you can and should use every day as part as any normal makeup routine.
Bottom Line: I wouldn't want to be without these brushes.
Hakuhodo S121G ($38) and S133 ($34) Eye Shadow Brushes are available online from hakuhodousa.com.
All photos are mine.