Guardian: Saviors of Kamigawa

Guardian: Saviors of Kamigawa is the final novel in the Kamigawa Cycle, which started in Outlaw: Champions of Kamigawa and Heretic: Betrayers of Kamigawa. It is written by Scott McGough and published in May 2005.

Blurb
The victory of the spirit world is at hand.

The ronin Toshi has sought to avoid the great conflict between the spirit and human realms. But despite his best efforts, he's not only involved in it, he's at the center of it. Together with Princess Michiko, daughter of Daimyo Konda, he must find a way to stave off the impending victory of the kami, while preserving his own life into the bargain.

Amid the complicated maneuvers of the fox people, the moonfolk, and the Daimyo himself, Toshi can rely on only one person.

Himself.