Kakashi accidentally traveled to the heroine's world due to human experimentation. Due to the mutual repulsion of the world, everything about Naruto in the heroine's world disappeared at the same time. Under the attack of an illegal organization, the truth of the matter was revealed step by step, the truth that the heroine had tried hard to hide.
This article does not have a relationship between the heroine and Anbu Kakashi. She treats Kakashi completely as a younger brother. Obito will appear in the second half (I am an Obito party). The heroine is not a Mary Sue and likes to be a demon. There is a plot of her soul exchange with Obito later, which is very funny.
This article is also available on Tieba. Because it is inconvenient to post there, I also registered an account here. (The writing is not very good, but please take care of me!)