While the Naraku had begun their assault on the Milky Way Galaxy, the Empresses which ruled over the two invasion forces remained within their respective galaxies. After all, if either of them were to be killed, it would be disastrous for the entirety of the invasion.
But things were not progressing as they expected. Resistance was definitely stiffer than they had previously estimated. Sure had been decades since they received any information regarding their opponents and their strength.
Yet that did not explain how they were capable of resisting two entire galaxies worth of Naraku. At least, to which they were currently doing so. By now, only a few hundred worlds on the fringes of the galaxy had been successfully invaded by the Naraku.
And that was only in 4/5s of the galaxy. In one very specific portion of the Milky Way, the Naraku fleets send to invade it were suppressed at the border. Seemingly losing their forces faster than they could be replaced.