I Got Reincarnated As My Own Long Lost Sister But I’m Actually Ok With This?

Isekaied. Reincarnated. Or just plain cursed. Whenever me and my best friend started daydreaming about this stuff it always had the same ending: "Oh no, I somehow got turned into a girl!" Except I always knew that sort of thing didn't really happen. That is, until the day it actually happened to me! And you know, in retrospect there were a lot of questions I should have asked when that mysterious lady offered to bring me back to life if I promised to help her out with some stuff? But in my defence, it was my first time being dead and I was a little uptight about it. This is the first installment of our 'Mara-verse' series. — Description from novelcodex.org