HAKU is whitening essence that available in Japan and Taiwan only. I bought it in a drugstore in Tokyo. There was promotion for HAKU and a package with 2 bottles of 50g and 1 bottle of 20g only costs around 10,000 yen (approximately USD150). I only apply it at night after toner and before night cream. Its textuer is light and gel like, and does not leave powdery texture like some brightening products. In summer, I do not need to apply moisturizing serum separately. But in winter, I apply Avene Smoothing Serum before this product. It took me around 2 weeks to see the effect - my face tone looks even, brightened and clear. It is very gentle and not irrating, with light yet pleasant smell. A great product but too bad it's unavailable in Hong Kong. I will buy few more sets when I travel to Japan next time. I think it beats Sekkissei. If I can't get this, I would probably try Dior SNOW.