Japanese folks came to the surname accessory late in the trend. Noble families were allowed to have them, peasants weren't. Thus, when the populace at large were made to get surnames during the Meiji restoration, they tended to pick names descriptive of their geographic location (hence a lot of folks with surnames of XXX-field or YYY-village. Yoshida: Goodfield. Kimura: Tree-village).

The colors most often featured in their surnames are landscape colors-- black, white, green and blue. Kurosawa: black river. Aoki: green tree.
http://www.jref.com/language/japanese_surnames.shtml