Rebirth As a Fatuous and Self-indulgent Ruler - Chapter 451 - To Kill King of Three (II)

The ordinary 18-year-old Edo, during a nighttime walk, finds himself in a fantasy world where he gains a mysterious power that could shape his destiny.

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

16 years old-- most boys would be falling in love, as their hormones all rise to unprecedented levels. Most boys at Riley's age would have dreams; dreams that will slowly grow into passion. Riley, however, at age 16... killed the world's number 1 superhero.

The world froze.Literally froze. The chattering students, the falling cherry blossoms outside the window, even the dust motes in the air – all suspended in perfect stillness.“Oh wonderful hero,” a melodious voice echoed through the room. “Your world faces a terrible crisis, and you have been chosen to—”“No,” he said flatly.A pause. Then a shimmer of golden light coalesced into the form of a beautiful woman in flowing robes. She blinked at him. “I... what?”“I said no. I'm not interested in whatever quest or destiny you're selling. Pick someone else.”The goddess's perfect features creased in confusion. “But... but you've been chosen! The prophecy speaks of a warrior with a fierce spirit, one who—”“Lady, I don't care about your prophecy. I've got enough problems here without adding some fantasy world's issues to the mix. Now un-freeze time and leave me alone.”“You don't understand,” she pressed. “Our world is being ravaged by the Demon King's armies! Millions will die without—”