Because I Was Excluded Out of the Class Transfer, I Decided to Steal My Classmate's Lover - Chapter 61.4: Slightly distorted sexual preferences Part 1.

(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.”

Framed by her family, she had an accident, and found herself pregnant!Five years later, she came back strong, determined to crush those who wronged her and reclaim her child!Her genius son paves the way, swiftly bringing her to the top of the food chain, with influential figures bowing to her!But she never expected that the autistic little girl she unexpectedly met would bring her a troublesome big boss!Before marriage, he holds the little genius's hand, declaring, “Buy a kid, get a dad for free, no deception, unrivaled in punishing scumbags!”After marriage, he kneels on durians with the child, saying, “Sweetie, I'm sorry, our hidden identities have been all exposed...”

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

Fear breaks the boundaries between dreams and reality, and it is impossible to tell which is reality and which is illusory. When the nightmare really comes, no one can be alone.

This is both a danger and an opportunity.

- Description from novelbuddy