Naruto: The Nine-Tails Fox in My Second Life

[Transmigration + no System + no pairings + original characters + classic wish fulfillment + characters stay in character + Minato-focused early on, transitioning to Naruto later]

On the battlefield, Naruto and Sasuke faced the formidable Ōtsutsuki Isshiki, who wielded the power of Karma and could easily overpower them in Six Paths mode. Kurama, the Nine-Tails, had already forged a bond with Naruto that would last a lifetime. To protect both Konoha and Naruto, he willingly helped Naruto activate Baryon Mode.

[Is this as far as we go...?]

At last, Kurama's life force was completely spent, and Naruto left Baryon Mode.

After saying his final goodbye to Naruto, Kurama closed his eyes in exhaustion.

[We've never been apart since the day you were born, have we, Naruto? From here on, you'll have to walk your own path.]

Just as Kurama thought his soul was about to depart for the heavens, a powerful life force suddenly surged through his body. When he opened his eyes again, a full moon hung before him, and beneath it, Minato Namikaze had just rescued Kushina from danger.