Hakuhodo G5529 is an eye shadow brush made of soft blue squirrel hair and shaped into a narrow and directional head, very efficient for detail work: smudging, smoking out, defining the crease or the lash line and also highlighting the inner corner. The hair is packed firmly enough to give the head some serious balance and heft, while still maintaining flexibility and bounce. It's also quite impossible to tug and pull the skin with this soft Hakuhodo brush.
Hakuhodo G5529 is very similar in shape, size and performance to the classic Shu Uemura 5R (the one with the lighter hair in the photos above), so I use them interchangeably. The latter is made of pure kolinsky hair and as such is significantly more expensive ($60), but I have to admit that I like the G5529 just as much if not more because it's so precise yet incredibly soft. Granted, my Shu 5R is significantly older, but I don't think that's the reason. The flexibility and luxurious feel of Hakuhodo G5529 are the reasons it's a favorite.
Bottom Line: an essential.
Hakuhodo G5529 Eye Shadow Brush ($28) is available from hakudousa.com. They ship all over the world.