Novel's Extra: I Awakened The Strongest Physique From The Start - Chapter 266 - 267 - Merged Floors 1.

A man is reborn into the world of Avatar: The Last Air Bender as a waterbender from Katara's tribe. Best of all, he was the same age as her, and he had a system with him to help.He knows the future and a system that lets him continuously get stronger by completing quests or long-term missions, as well as giving him the ability to copy abilities from others for himself. He will become invincible in the world of Avatar, even more so than the Avatar himself.

Captain America: “Commander! The roaring commando is in place!”
Iron Man: “You are my godfather?!”
Wolverine:……
Dark Night Legend, Avatar, Bliss Space, Transcendental Hacker…

Traveling through the world of science fiction movies, and quietly changing the real world
A dark mech slowly landed on the platform

“Boss, the press conference is about to begin.”

- Description from Uukanshu translation

Hakuto's life changes forever when his father Shin— a man with highly questionable morals—marries Kagura Kurotsuki, the CEO of a multinational company, and they move into her luxurious mansion.There, he meets the alluring daughters of his new stepmother: the seductive Yuzu—who doesn't hesitate to tease both her new stepbrother and her stepfather in ways that are... rather bold—and Rika, more introverted and irritable, yet just as sensual.But nothing is truly as it seems...Kagura is a succubus, but Rika and Yuzu are different.They were born from a demon and a vampire—something that shouldn’t be exsiste.Because of that, demons, vampires, even humans want them.But Hakuto won’t allow it.He’ll never let anyone hurt his beloved stepsisters.