Samurai of the Sun is the 19th Proposed Serial of Spectral Shadows. It is preceded by Serial 18 - The World of the Anthrodroids succeeded by Serial 20 - Oops, Wrong Planet. This serial is currently not in the works, and the only material available is the summary from the Synopsis Page.
The summary is as follows:
As the quest for a perfect world for anthropomorphic refugees continues, the crew of The Rocinantè find themselves on a furry feudal planet - caught up in the conflict between two warring factions, but not certain which is the right one to side with.