Just like the Republic of Gorteau and the Britannian Empire, the Sekigahara Confederate was also displeased by the return of the Emperor of Harmony for their own reasons. They were the most ideologically opposed and antithetical to the Emperor of Harmony.
While they respected his capacity in war as the supreme commander of the Kandrian Military, they deeply abhorred the philosophy that had come to embody his politics.
"The Emperor of Harmony," the matriarch of the Tsukishi Clan grumbled. "Coming back and calling for a C16 meeting from the start. Who does he think he is?"
"…It's just like him," the patriarch of the Kenjin Clan narrowed his eyes. "Of the four powerhouses, he was the one who initiated cooperation the most."
The Republic of Gorteau sought war for profit, while the Britannian Empire simply sought war because it was a state that was led by Martial Artists who needed physical conflict to grow.