During volumes 37-39 Yakumo and Pai became human during the Humanity Ritual and Pai separated herself from the her Sanjiyan personality. Sanjiyan gets absorbed into Kai Yan Wang. Human Pai goes off on her own to try to save Sanjiyan. Volume 40, Yakumo tries to find Pai, but she finds Yakumo (who is barely alive) instead. He begins telling her not be reckless cause she is human now. Later Kai Yan Wang starts absorbing Yakumo. Then as he's about to completely absorb Yakumo, he stops. Sanjjiyan emerges from within Kai Yan Wang. Sanjiyan tells Pai to merge herself with Sanjiyan again. As Yakumo's friends are fighting Kai Yang Wang and Benares, Sanjiyan performs the immortal spell. As this happens, Yakumo, who was already on the verge of death from the beating Benares gave him as a human, rose up again with the Mark of Wu on his forehead. So Yakumo and Sanjiyan go into battle. Uber Yakumo ends up destorying Dragon form Benares and defeats Kai Yan Wang with all the power he recieved from all his friends, the power of "LIGHT".
We see Yakumo embracing Sanjiyan who tells him he did great job. Her thrid eye close and Pai starts confessing her love for Yakumo again. Yakumo tells Pai that they can finally live together with some peace. Kali (Pai's clone), took what was left of Kai Yan Wang's body and left. With Kai Yan Wang beat, poweruped Yakumo still had all the power from his friends souls, but needed to release it to set them free. So he told Pai to destory his body so he could release that power to set them free. Yakumo tells Pai that as long as he lives, he'll find Pai, so she should wait for his return. Sanjiyan lets out a blast and blows up Yakumo into pieces.
After this we see events that take place after the battle. We see Yakumo's friends who are all doing well. We then see Kali (Pai's clone) who is riding on Takuhi, with a large figure (Benares) at her side. She tells him that they'll watch over the actions of mankind, so they don't lead to destruction. Till then, they'll protect them for now. The figure replies, "Yes, my Master!". Kali ended up merging with Kai Yan Wang, therefore she is Kai Yan Wang. Elsewhere, Sanjiyan is riding on Fei-Oh dicussing she wants Yakumo, since he's her servent and falling for her charms. Pai declares she likes Yakumo more. Then the 3rd eye pops up and Sanjiyan says that the decision is Yakumo's to make. The 3rd eye disappears and Pai agrees with Sanjiyan. Next we see a lonely figure, while you don't see his eyes, it is blatantly obvious who it is because you can see his hair. A teary Pai/Sanjiyan then says that as long as Yakumo is alive, they will reunite some day.
The END!
3x3 Eyes is my favorite anime/manga of all time. I love my Yakumo avatar, just as I love the series.