Besides the abnormalities in Katsuya Uchiha's body and his Mangekyō Sharingan, there was something else that deeply concerned Hiruzen Sarutobi and the others: his eerie, mirror-like secret technique. So far, Katsuya had used it to evade lethal attacks again and again. It was terrifying.
Judging by appearances alone, Kagami Uchiha could not help thinking of the legendary secret technique passed down through the Uchiha Clan—Izanagi. At the cost of one Sharingan, Izanagi could rewrite reality for a limited time, turning unfavorable events into dreams. It could even avert death.
Upon reaching the level of the Mangekyō Sharingan, not only did its duration increase, but a technique could also be sealed within the eye and given specific activation conditions. Even if the user did nothing, the Mangekyō Sharingan would activate automatically once those conditions were met. This was the Transcription Seal, a technique available only to the Mangekyō Sharingan.
Back then, Madara Uchiha had prepared for his defeat at Hashirama Senju's hands by inscribing Izanagi into his Mangekyō Sharingan, setting it to revive him after a delay. He had assumed that Tobirama Senju would preserve his body no matter what. As long as his Mangekyō Sharingan remained intact, he could rewrite reality and return to life.
However, because Kazemori Masaki had intervened, Tobirama could not substitute Madara's body in front of his sister-in-law with everyone watching. He had no choice but to let the others cremate it. Once the Mangekyō Sharingan was gone, the Izanagi inscribed within it could no longer activate.
Still, using Izanagi required sacrificing a Sharingan. With only one person's eyes, it could at most save their life in a desperate situation, not be used indefinitely—unless they possessed a large stock of Sharingan. In the Uchiha Clan's history, those who had abused Izanagi had continually taken their clansmen's