Aetheral Space - Chapter 39:3.2: The Halls of Power

Doomsday was approaching…

A supreme expert in the Immortal World had died, and a strand of his soul returned to its original body on Earth. Tang Xiu discovered with amazement that ten thousand years passed in the Immortal World, yet only a single year passed on Earth.

Ruthlessly betrayed by his lover and trusted friends, Tang Xiu found that his soul went back to his previous body on Earth, and, despite he spent 10,000 years in the Immortal World, just a year has passed on Earth and many things have changed. Having an unsurpassed knowledge, Tang Xiu will protect his loved ones and go back to the Immortal World to take his revenge.

- Description from Novelupdates

(Naruto + Single Heroine Tsunade + Romance + Action)A failed author transmigrates into the Naruto world, becoming the younger brother of Konoha’s White Fang, Sakumo Hatake, and the uncle of Kakashi. He gains a cheat ability—enhanced cellular activity.Coincidentally, just before the Second Shinobi War, he participates in a Jonin meeting where he supports Tsunade's proposal ahead of Dan Kato, marking his first encounter with her.From then on, he launches an intense pursuit, winning her heart during the war.Tsunade: “Kawakaze, why do I keep losing to you?”Kawakaze Hatake: “Because I’d like to live a few more years...”Kakashi: “My uncle is amazing, I’m his biggest fan!”Kawakaze Hatake: “Keep it low-key, keep it low-key.”

Three thousand years of bowing down to the Demon Lord, I would rather be a mortal than a celestial being when looking back, but for her I will… become one who controls life and death!