Naruto: Neji Opens the Eight Gates and Achieves Immortality

Transmigrating into the Hokage world, I become Neji, branded with the Caged Bird Seal and left fatherless.

Because my soul transmigrated into his body, the Byakugan evolves, granting me the ability to commune with the dead.

Knowing that ninjutsu will be hard-countered later on, Neji chooses to focus on taijutsu and senjutsu, using ninjutsu as a cover.

First, he trains with Might Guy in the Eight Gates, then learns the Strength of a Hundred Technique from Tsunade.

Using his ability to commune with the dead, he finds Shikkotsu Forest and Water Curtain Cave, gaining Shikkotsu Forest's exceptionally potent healing senjutsu and the indestructible body technique of Water Curtain Cave's Demon Ape Clan.

When Madara is revived, the one standing before you is Neji, with the Eight Gates open and an indestructible body: “Just so you know, even with all Eight Gates open, I can still fight all day.”

When Kaguya is unsealed, the one standing before you is a muscular Neji, even more tempting than the Reverse Harem Technique: “Strictly speaking, you're an ancestor of the Hyuga Clan, so this would violate moral conventions. But I'm not actually a Hyuga.”

When Momoshiki descends, your buddy doesn't use ninjutsu: “The only thing you can absorb is the thrill of a punch landing squarely.”

When Isshiki, and even the God of Ōtsutsuki, descends, sorry, your buddy has already achieved sainthood through the flesh: “Just a heads-up, where I'm from, anyone who achieves sainthood through the flesh has a habit of slaying gods.”