Obito Uchiha lay on his back on the experiment table, recalling the harrowing scene that had taken place not long before.
With the outbreak of war in mind, Obito had prepared to implant the Rinnegan he had retrieved from Nagato.
Because of the Demonic Statue of the Outer Path, which was also the Ten-Tails, the Rinnegan was essential to controlling them properly.
So after Nagato's death, if Obito wanted to control the Ten-Tails, he had to implant the Rinnegan in himself.
Obito and Black Zetsu had discussed this before and decided that Obito would receive the Rinnegan transplant once war broke out.
However, because Obito's constitution differed from Nagato's, his body could not fully bear the burden of a pair of Rinnegan.
According to the plan, Obito therefore intended to implant only one Rinnegan. As long as it did not affect his ability to control the Ten-Tails, that would be enough.
Of course, a plan was just a plan. Before the transplant, Obito had a sudden idea. Considering the pressure Shihōin Naraku put on him, he wanted to test whether he could actually withstand a pair of Rinnegan.
Although Black Zetsu strongly disapproved of Obito taking a risk at such a critical moment, he also took the problem of Shihōin Naraku into account and thus expressed his support in a roundabout way.
Besides, there was something Black Zetsu had never told Obito: he had previously modified Obito's body.
He had kept this secret all along.
Although Obito occasionally had his suspicions and felt that something was wrong with his body, he was not entirely sure.
Most importantly, Obito thought the problem with his body was caused by a contingency Madara Uchiha had left behind.
Indeed, by this point, Obito had already noticed that Madara Uchiha had left a special cursed