The Replacement of the Sword Hero

In this timeline, Ren Amaki no longer exists.
Inexplicably, I found myself summoned into the world of a light novel series I was reading and ended up completely erasing one of the supporting characters. Now I must fulfil my role as the Sword Hero's replacement and hopefully avoid making the same mistakes he did using my knowledge of future events I have gained from reading the series.

(This is a Fanfiction. These events are entirely non cannon but spoilers from the series and spin offs are mentioned. Please support Author Aneko Yusagi by purchasing their works.)