I have always been fascinated by Japanese culture and style and decided to put together the following suggestions.
Today's decorating trends are all about globalization. As different cultures discover each other, they also appropriate traditional and modern elements of local interior design. Japanese influences were one the first to find their way into the multi-cultural design repertoire, and it's easy to see why. Japanese culture is famous for its clean lines and use of natural textures, from bamboo to thin rice paper.
Bamboo wood blinds, which are also called woven wood shades, are a subtle and simple way to start off. Not only are they aesthetically pleasing and easy to use, they also offer high levels of light control and privacy. Another popular wood for Japanese window treatments is tatami, which is a thick woven read with a warm, natural texture. Both of these wood blinds can be stained to compliment an interior color scheme.
Depending how far you want to take your theme, you can also look into sliding paper screen for your Japanese window treatments. These are a striking solution for covering unusually sized plate glass picture windows. Also known as shoji screens, these sliding screens offer a pleasant degree of light diffusion but do not provide complete blackout capabilities.
Though curtains are not inherently Japanese, many designers look to traditional textile prints for inspiration. These prints, often found on kimonos and other clothing, can include everything from geometric designs to fanciful scenes of carp or eagles. These fabrics are usually employed as short hanging curtains, and can also be fashioned into café curtains that subtly mimic the traditional hanging noren curtains found at the entrance to Japanese restaurants.
Another option window treatments are panel track blinds, also know as sliding panels. Though not specifically Asian, panel tracks can lend to this kind of decor readily. These window treatments are like oversized fabric vertical blinds and come in numerous colors, fabrics and textures. Panel tracks can also be used as a room divider, mimicking the Japanese sliding paper panels.
Last but not least are roman shades. Though, again, not specifically Asian or Japanese per say, the right fabric and texture choice could lend itself well to this kind of décor. In my opinion, the best type of roman shade for this application would be the flat-style, not the hobbled or folded roman shades. Romans come in bamboo weaves, grasses and wood planks that would match well with the Japanese style of decorating.
A quick word of warning from personal experience - I have seen a few homes that have been decorated well in this style. And, kudos to those who have the vision, passion and artistic sense to pull it of; it is a bold choice, for sure. I have also, unfortunately, seen examples that did not integrate well or were taken too far. So, if you are interested in this motif, consider integrating subtle elements one step at a time and make sure you don't have clashing decorative motifs.