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.

After waking up, Shen Fan traveled to a world of chaos and war, where demons were rampant, and his martial arts aptitude was mediocre.

However, Shen Fan discovered that as long as he made a breakthrough in his martial arts, his lifespan would increase, and his talent and potential would continue to improve!

From being an ordinary person to becoming an immortal, Shen Fan said that all this was the result of his own hard work!