I'm no expert on this subject, but I have a book entitled Japanese Military Uniforms 1841-1929 by Ritta Nakanishi which is filled with color plates; notes are in both Japanese and English. According to that book the standard equipment used in the Russo-Japanese War was set in 1886. It shows uniforms in dark blue, khaki, and white and combinations of all three. Basically it supports what James said and indicated that a mix of uniforms and parts of uniforms prior to the 1886 standard were all in use.