Sasuke spent the next week in Orochimaru's library, surrounded by scrolls and medical texts.
His Mangekyo had opened possibilities. But he needed to understand the mechanics. How Takama-ga-hara actually worked. What the limits were.
"Still researching?" Kabuto entered with medical reports. "You've barely left this room."
"I need to understand the process before I test it extensively."
"Smart. Mangekyo techniques can backfire if misused." Kabuto set down the reports. "What have you learned?"
Sasuke gestured to his notes. "Takama-ga-hara doesn't just copy dojutsu. It absorbs the ocular chakra structure permanently. Integrates it into my own eyes."
"That sounds... extremely dangerous."
"It is. If I absorb incompatible dojutsu, it could destroy my eyes from the inside." Sasuke pulled out a diagram he'd drawn. "That's why I need to understand compatibility first."
The diagram showed different dojutsu families. Sharingan variations in one branch. Byakugan in another. Rinnegan at the top.
"The Sharingan evolved from Rinnegan originally," Sasuke explained. "Same root source—Hagoromo Otsutsuki. So absorbing other Sharingan should be safe. They're the same family."
"And Byakugan?"
"Different branch. Hamura Otsutsuki. Related to Sharingan distantly, but different evolution path." Sasuke tapped the Byakugan section. "More risk. But manageable if I'm careful."
Kabuto studied the diagram. "You're planning to absorb multiple dojutsu types?"
"Eventually. But I need to understand absorption mechanics first." Sasuke activated his Mangekyo briefly. "Ryota's Sharingan integrated smoothly. Two-tomoe, weak, but the process worked. Now I need to test on a different bloodline."
"Byakugan?"
"Yes. But carefully. The first cross-family absorption is the most dangerous." Sasuke deactivated his Mangekyo—the drain was still significant. "My body needs to learn how to accommodate foreign dojutsu structures."
Kabuto picked up one of Sasuke's research scrolls. "This is remarkable work. You've theorized the entire process. Orochimaru-sama would be impressed."
"Has he mentioned anything specific?"
"Constantly. He's fascinated." Kabuto's expression became calculating. "He wants to study the absorption process. Map the chakra structures. Understand how it works at a cellular level."
Of course he did. Orochimaru wanted every secret Sasuke possessed.
"Tell him I'll allow examination. After I complete my first Byakugan absorption." Sasuke gathered his notes. "I need to know if cross-family integration is viable before I commit to large-scale hunting."
"And if it's not viable?"
"Then I adjust my strategy. Focus solely on Sharingan collection until I achieve Rinnegan." Sasuke's eyes gleamed. "But I suspect it will work. My Mangekyo was designed for this—collecting all divine sight, not just Uchiha eyes."
"When do you plan to test it?"
"Soon. First, I need to locate an appropriate target. Isolated Hyuga branch family member. Weak enough to defeat easily, but strong enough to have developed Byakugan." Sasuke pulled out intelligence reports Kabuto had provided. "Do we have updated information on Hyuga positions?"
"I'll compile it." Kabuto stood. "This will take a few days. Use the time to prepare. Byakugan absorption will likely be more painful than Sharingan integration."
"Pain is irrelevant." Sasuke returned to his notes. "Results are what matter."