Become a Demon King from Naruto

Because of a heavy rain, Yujiro Fanma passed through the world membrane and came to the world of Naruto. As cautious as he is, he spent three years observing the world carefully. During these three years, he was diligent and studious, hiding himself and joining a strange village called Konoha. I heard that he is the strongest among the five great ninja villages in the world. Now, he wants to be apprenticed to a watermelon-headed weirdo in green clothes... This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.