Shinobi World No. 1, southern Land of Fire, deep within Danzo's territory, in a top-secret base converted from a natural limestone cavern and covered in layers of seals.
The air was thick with the smell of blood, the pungent odor of preservatives, and an indescribable residue of spiritual contamination produced when souls were forcibly blended and twisted together.
Sickly green lights illuminated a cleared circular area at the center of the base. A vast, intricate summoning array had been drawn on the floor in a special dark red substance that seemed to squirm faintly.
Scattered around the array were the corpses of sacrifices whose souls had just been extracted, their faces twisted and rigid, along with glass containers holding unidentified organs and tissues.
Orochimaru stood at the edge of the array, fatigue, excitement, and a researcher's singular concentration gleaming in his golden, slit-pupiled eyes.
He extended his long tongue and licked his slightly cracked lips. Watching the specks of chakra light and dust gradually gather and solidify at the center of the array, he gave a hoarse, satisfied chuckle.
"Heh heh... it worked. The sacrifices varied in quality, and the soul connection is still a little sluggish, but the compatibility with 'that lord's' soul characteristics is quite high. At its current level of completion... he should be able to consistently wield roughly half the strength he had at his peak. And thanks to certain... subtle relaxations in the 'external environment,' controlling him has been somewhat easier than expected."
The "relaxations in the external environment" he mentioned naturally referred to the slight easing of restrictions on Hashirama Senju's soul, with the Sage of Six Paths' "tacit approval" in the Pure Land.
But Orochimaru had no way of knowing the reason behind this, attributing it only to his improved skills and "luck."