Land of the Dead

It's a small change in our history: imagine that the Japanese made contact with the Aztec Empire. Instead of small-pox and Christianity, they brought an Imperial alliance, samurai ethics, and technology. By the time of these books, the Emperor in Mexico City rules not just the entire planet Earth, but a growing interplanetary Empire. But the Galaxy is not a hospitable place, and there are other powers, both new and very very old, who would stop the spread of the power in Anuhuac.