[POV: Sage of the Six Paths]
[Scene: The Pure Lands]
[Track Change: Undertale 'Mysterious Place']
'After a long rest I have finally regained enough Chakra to watch over the world safely, it's been too long, hopefully the world is still intact after Mother was sealed.'
The Sage of Six Paths, Hagoromo Otsutsuki, after recovering from the loss of vitality from splitting the 10-tails (Juubi), started to watch over the ninja world, however the situation was far from what he envisioned. 5 large countries, many smaller ones. The Ninshu Creed being seen only in Monks and the Ninjutsu his son Indra created being used for war, lots of war, so much war that seemed to be sparked from nothing, a simple verbal argument was enough to cause hundreds of deaths. Hagoromo was confused, why go so far over something so minor?
Hagoromo scanned through time using a space/time jutsu he created during recovery. What he found shocked him, every war, nearly every large-scale battle was triggered by one being or its earlier actions, over tens of hundreds of years, this being had caused nearly 3 million deaths, with only words and manipulation. Hagoromo after observing this being learned its name, Zetsu, and its goal, the revival of Kaguya Otsutsuki, his mother. Zetsu was made of his mother's Yin-Yang Release, created with the sole duty of unsealing Kaguya.
Hagoromo's brow furrowed, he could not believe this being could cause so much hatred and death. The most unfortunate part, Hagoromo couldn't interfere! His body was dead, likely decomposed, he was only a SOUL in the Pure Land, and despite his bloodline, an old SOUL like his cannot return to the world of the living to possess a body without severe consequences. Looking at the present Hagoromo was even more appalled, Zetsu was manipulating his son's reincarnations! Indra's reincarnation, Madara had already acquired the Rinnegan and summoned the Edo Statue from the moon! What was Hamura doing!? Ashura's reincarnation had died, if Zetsu started his plan now, no one could reseal Kaguya!
Without any time to waste Hagoromo extended his sensory range throughout the Pure Lands looking for Ashura's Chakra, but before he could find it he noticed two Irregularities in the Pure Land, a Human SOUL with no Chakra, and another strange entity with an energy he had never encountered. Immediately, he teleported nearby, and overheard everything, from Asriel's introduction to the end of both stories, and Anthony's words to Asriel. Hagoromo understood at this time, neither of these entities had malicious or ill will. Both assumed correctly this was the afterlife, but Hagoromo knew it wasn't their world's afterlife, but the one of the Ninja World.
Realizing this, Hagoromo thought, 'From how they speak, it hasn't been long since either of them passed, their SOULs are in perfect harmony almost like they could combine without harm. A dual SOUL like that, with that small white one's body, could easily leave the Pure Land. I should speak with them, if they can agree to raise Indra and Ashura's next reincarnations and stop Zetsu, I can grant them a second life in the Ninja World. After all, I can't go myself, sending a guardian seems like the right move.'
With that thought, Hagoromo floated out from the darkness, and spoke in a deep gravelly voice, clearly strained from tens of hundreds of years of silence. "Indeed, you both understand this fact well. Few can move beyond their pain, but together they can grow and accomplish many things. You two remind me of my sons."