[Harapeko Cat (Roako)] Heroin ni Tensei Shita Boku wa Yuusha no Tame ni Onna ni Naru.

@flyfiy it's different, the plot is different. TS FMC didn't get reincarnated to a random isekai, he got reincarnated as a girl into a game world he made himself back in high school. Consequently she knows the characters and the plot, and what would happen to them. She knows that the hero mc is going to die because of that, and dreaded that inevitability as she has grown to like the male hero, first as a friend than as a member of the opposite sex. Things played out differently though, and they got together in the end. The only 'earthling' here is the FMC.

I'm not sure this is 'original', it looks alot like a manga I once read.. called "Reincarnated with my best friend, but I am the Heroine and He is the Hero" or something

i hope this will get translated