What is the rinnengan?

Rinnengan is the power of the sage of 6 elements

Pain/Nagato was able to use all 6 elementals.

What I personally think that is able to use mass jutsu with all elementals, but also if I am r

correct, that he has an affinity to all of them what also means that he maybe able to fuse

them together to one bloodline Jutsu or Rinnengan.

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