I may have the Mexican purchase of 7mm Arisakas conflated with the substantial Japanese immigration to Brazil at about the same time and it is possible that I am wrong about the Jap rifles going to Brazil, don't recall where I read that.
I'll dig this thread out of the basement in order to let vigillinus know that his memory was mostly correct.
A descriptive history of the Mexican Arisakas appeared in
The American Rifleman, November 1974, p.25, in an article by George A. Wiswell.
Here's a brief abstract:
In 1910, Japanese immigrants in Brazil imported Type 38 Arisaka rifles and carbines chambered in 7x57mm as part of a program to introduce Japanese products in South America. Brazil did not need these arms, but the Mexican government did. Some were shipped from Brazil to Mexico, and are known as Model 1910 Mexican Arisakas.
In 1911 the Mexican government was overthrown. The new government ordered more 7x57 Arisakas for the army's use against further revolution; these are Model 1913 Mexican Arisakas. The Mexican government could not pay for the Model 1913s, so they were sold to Russia in 1915 for use by the Czar's army. These were delivered in Manchuria, but during shipment to the European front of WWI, some of these Arisakas were appropriated by local Siberian forces. Americans in the 1918-20 Siberian Expeditionary Force encountered some of these.
The Model 1910 is marked either with three interlocked circles, or with the Mexican national crest with a left-facing eagle. The Model 1913 bears the modified post-revolutionary Mexican crest with the eagle facing right. Production of Mexican Arisakas is estimated at 80,000.
