Your Rinnegan Came from Madara Uchiha

Because Tsunade had suddenly appeared, the itinerary Kizaru had prepared for Nagato changed.

At Tsunade's insistence, Nagato, who had only just arrived in Konoha, was more or less forcibly sent to the hospital.

Faced with this sudden turn of events, Nagato was completely bewildered.

If he hadn't been fairly certain he'd traveled to another world, and if Tsunade hadn't already shown concern for him, he would have suspected the two of them wanted to conduct some kind of physical examination on him.

Once they arrived at the hospital, Tsunade arranged for Nagato to undergo a full examination.

The results could be summed up in two words: on his last legs. He didn't have long to live.

According to Tsunade, if Nagato avoided using the Rinnegan in battle, he might last another three to five years. But if he used it and pushed himself too hard, he could drop dead at any moment.

Nagato knew his health was already in terrible shape, but he hadn't realized it had gotten this bad.

There was no way Nagato could give up using the Rinnegan. At least until he had completed his revenge, he couldn't abandon his greatest source of strength.

But both his revenge and his ideals would take time, and he didn't have much time left.

To buy himself more time, Nagato chose to be obedient and follow Tsunade's treatment plan.

Although Nagato's health was in terrible shape, treating him wasn't especially difficult.

His main problem was that overusing the Rinnegan had pushed his body past its limits, consuming a great deal of his life force and causing him to age prematurely.

The treatment was simple: replenish his life force.

In Nagato's world, this treatment would have been very difficult. Perhaps only Chiyo's forbidden technique, One's Own Life Reincarnation, could have done