What Should I Do If My Brother Is a Reborn Villain?

High schooler Sayaka had a happy family and unexpectedly awakened a Stand.

Once, after mistakenly thinking a Stand User had attacked her older brother, she and her brother transmigrated to another world.

Then she learned from her brother that he was actually the behind-the-scenes boss in a manga she'd read, someone whose face had yet to be revealed.

Sayaka: You have to be kidding me!

*

After the Fourth Shinobi World War, Madara was preparing to return to the Pure Land. When he opened his eyes again, he found himself in an unfamiliar world.

His body had reverted to childhood, and he had become an "ordinary person."

After learning a little about this world, he chose to be adopted by a couple with no children.

Later, he got a younger sister, who started reading the hit manga Naruto in high school.

Uchiha Madara: ...

The good news: he hadn't appeared in the manga yet.

The bad news: when he turned twenty-one, his sister transmigrated with him back to the shinobi world.

*

After his elder brother returned from one of his outings, the Uchiha clan's second-in-command found that his brother hadn't come back alone.

His brother had also brought home a sister of unknown origin.

Izuna: ?

After confirming she wasn't an illegitimate daughter their late father had left behind, Uchiha Izuna became highly suspicious. What enemy had bewitched his big brother Madara?

He would never admit that this scheming girl was his little sister!

*

At first, Izuna warily asked his brother, "Big bro, you and her are really just siblings?"

Later, Izuna cautiously asked his brother, "Big bro, are you and Sayaka really just siblings?"

*

1. Izuna is the male lead. Madara's relationship with her is purely familial.

2. The story mainly takes place in the Fire Country. The modern-world setting is JoJo, in the 2000s, and the manga is up to before the Fourth Shinobi World War. The hand fetishist from JoJo has been dead for many years. The heroine is the same age as the strongest elementary schooler. There will be very little JoJo-related plot.

3. Aside from having a Stand, the heroine is an ordinary high school girl. She may play favorites, but she's still on the side of good. After transmigrating, she's genuinely worried Madara will go back to villainy.

4. It should be a romance-focused story... If it goes off track, I'll just delete this note.

5. I gave Madara so many advantages and went through so many hoops to make him her sworn older brother because I really couldn't think of a way to make pre-war Madara give up on the Eye of the Moon Plan.

6. The male and female leads aren't blood relatives and aren't registered in the same household.

7. I'll add more if I think of anything.

Theme: Love and peace.