Toaru Majutsu no Index SS - Volume 1, Prologue: The Calm Before the Start of War. Breakfast.

"Who touched you?" he asked, his eyes brooding down at her and when she didn't answer, his voice thundered in the room, "WHO?"

There was once an immortal cultivator fighting for the fate of human beings. Unfortunately, he failed that time; but fortunately got another chance as he was reborn once more as a human, on the earth of 5,000 years ago. With a second chance, he not only would embark on the road of saving all mankind, but also would retrieve his human nature on the new journey that would last for 5,000 years.

- Description from Novelupdates

After getting betrayed and killed by the only person she’d loved, Miss Shang wakes up in the body of the cowardly crown prince Shang Wuxin, who, due to her own circumstances, was actually a girl cross-dressing as a boy. After inheriting the crown prince’s memories, Shang Wuxin has three things on her agenda:

1. Clean up the house

2. Gather loyal followers and soldiers

3. Get the throne

Thanks to the so—called God, I somehow ended up as Uchiha Itachi’s younger brother and Sasuke’s twin.Wild, right?If I had to sum it up, I’d say, “Losing Shonen Jump is one thing, but losing your integrity? Now that’s a tragedy.”But let’s be real—none of that matters when you’ve got the Gojo System from the get-go. Yeah, you heard that right. From the moment I landed in this world, I was set to flex on the entire ninja world.And just like that, Konoha got itself a brand-new, utterly bizarre Uchiha.