My favorite two Japanese photographers are,

Kayo Ume ( http://japan.digitaldj-network.com/archives/51856149.html) She doesn't have official site so I attach twitter's page that upload lots of her photos.

and

Mika Ninagawa (http://www.ninamika.com/en/photographs/index.html : English site).

Kayo's photos are soooo amusing and humorous. She takes photos of everyday life that we take for glanted and neglect. Once you see her wokrs, you'll sware to bring your camera with you everyday not to miss funny timing!

Mika's photos are all vivid colour and wonderful! She is well know in Japan and abroad.