This is a pretty tricky situation. Most hair-color products on the U.S. market just don't work well on Asian hair, which is the thickest of all hair types. More often than not, any amount of lightening turns out brassy; even black comes out looking unnatural much of the time because it's a difficult color to match. Your best bet is to go to an experienced colorist. If you decide to try it at home, remember that thick hair tends to absorb dyes fairly quickly, and very dark hair is especially resistant to bleaching, so always do a strand test to get the timing right.