I recommend the novel Natsume's Friend: Returning to the Youth with Takashi Natsume to you. This was a doujinshi novel. The main character traveled back in time to Takashi Natsume's childhood and became his childhood sweetheart. There is no sex change in the story, and Takashi Natsume is not feminine, so you can read it without worry. I hope you like this fairy's recommendation. Muah ~😗