Sōunga had originally been one of the Dog General's three mighty swords.
Unfortunately, that older man had passed away.
And the Ancient Evil Spirit within it was not something Sesshomaru's mother could suppress.
Well, even if Sesshomaru's mother could suppress the Ancient Evil Spirit within Sōunga, retainers like Totosai had no intention of handing Sōunga over to Izayoi or Sesshomaru. (Those who knew, knew.)
The dog family really was "riddled with factions."
As for Li Xia...
Faced with the bottleneck blocking his path, he finally decided to make the Ancient Evil Spirit his target.
As long as he purified the Ancient Evil Spirit, the essence he received in return would be enough to transform half his Yin Spirit into a Yang Spirit, allowing him to advance another step.
He had granted Transference to the Demon Souls of Iron Chicken and her daughter, granted Transference to the lingering thoughts in Naraku's scraps of flesh, purified the Evil Aura on the Banryu Great Spear, and granted Transference to the Flying Demon Moth's evil soul; afterward, he had granted Transference to Ryūkotsusei's dragon soul, Shinigami Oni's Ghost, and the Four War Gods' resentful souls, and received gifts from Mount Penglai's countless fireflies and the Miko Kanade...
Only through all these accumulated gains had he reached his current bottleneck.
Once he crossed this great hurdle, he would count as a great cultivator of this era.
His abilities would definitely surpass those of powerful Miko like Tōko, Kanade, and Kikyo, who had reached that level in only one respect.
He would also be a little closer to the heights Master Hakushin had reached.
The question was, how could he lure out the Ancient Evil Spirit within Sōunga and purify it?
The Dog General's solution had been to seal Sōunga using the combined abilities of Tessaiga