Monsters Descend: I Can Summon Pets Unlimitedly - Chapter 9: The Battle Against Puppet Monsters in the Cold Storage

A boy from 21st century Earth, met an accident and later was reborn in Naruto’s Ninja World.
He is born in Uchiha Family and becomes the useless brother of Itachi Uchiha and Sasuke Uchiha…. Let’s see how he changed the Naruto world.

- Description from Novelupdates

Leo awakens in a world he doesn’t recognize, with no memory of who he is or why he’s there. All he knows is that survival isn’t just a necessity—it’s his only chance to uncover the truth.Thrown into a brutal test for assassins on a hostile alien planet, Leo quickly discovers an extraordinary instinct for combat and evasion—abilities that feel second nature, yet remain a mystery even to him.But as the blood-soaked trials unfold, whispers of his lineage begin to surface. In a universe where gods are eternal and invincible, Leo carries the blood of the one being who defied that rule: the Timeless Assassin, a legend feared by mortals and deities alike.Now, hunted for what he represents and burdened by a legacy he can’t yet comprehend, Leo must forge his path through a deadly labyrinth of enemies, alliances, and cosmic conspiracies—all while piecing together the fragments of his forgotten past.For in the shadows of his fractured identity lies a truth that could shake the heavens themselves.

Going for a swim, she ends up in an ancient wild Beast World and ends up being brought home by a handsome wolf.

“How did you board the Astral Express, walk the Path of the Stars?”“Because I ended the Honkai, altered everyone's fate.”“So your first step on this path was becoming a hero?”“No, it was for survival, searching for a thigh to cling to.”“And then?”Ryan adjusted his glasses, his voice resounding.“I became the thigh.”