It was tall, at least fifty meters. Its trunk was dark red, its surface covered in bark-like patterns, but those patterns slowly writhed, like pulsing blood vessels.
Its branches spread in every direction, bearing no leaves, only countless dangling tendrils that resembled nerve cords.
At its crown sat a huge structure resembling a flower bud. The bud was tightly closed, but dark red light seeped through its seams, brightening and dimming rhythmically like a beating heart.
What frightened Naruto most was what surrounded the Mother Tree.
Those were... people.
Or rather, they had once been people.
Over a hundred "people" hung around the Mother Tree, bound in vines.
There were men and women, young and old. Their skin had all turned dark red, their eyes were closed, and their expressions were peaceful, as though they were asleep.
But their bodies were merging with the vines-the vines pierced their skin, burrowed into their muscles, and connected to their bones, as though drawing something out, yet also pouring something in.
Naruto saw familiar faces.
They were several Arrancar he had seen outside the training grounds a few days earlier.
They had been laughing and chatting then. Now they had become "fruit" on the Mother Tree, being altered and absorbed without knowing or feeling a thing.
"What... is this..." Naruto murmured.
"It's 'assimilation.'"
The Forest Guardian's voice sounded in his mind, transmitted telepathically through the Ancient Tree's roots.
"The Mother Tree is absorbing their reiatsu, memories, and personalities, then using those 'nutrients' to reshape their bodies and turn them into Ōtsutsuki 'soldiers.'
"See those cocoons? Those are the ones halfway through assimilation. These people are almost finished. Once they open their eyes, they won't be themselves anymore. They'll be Ōtsutsuki puppets."
A chill ran through Naruto.
He remembered Liuyu's words: "The Ōtsutsuki Clan