This book is also called "Soman: The Demon King Who Started the Naruto World"

[No system + multiple worlds + no qualifications to become Kamen Rider + multiple heroines + Demon King + OOC apology]

My name is Tokiwa Sougo, but I am not the little devil king, nor the old devil king. I am Tokiwa Sougo who traveled to the world of Naruto. I had no inheritance and felt that my life was over. But when I was just five years old, my complaints were heard by the old devil king, and I got an unexpected inheritance.

Tokiwa Sougo: I'm not a knight, I'm a demon king.