Lost Memories Lost Wind

In the past no one remember anything there were once legend about the first ever dragon the soar high in the sky but ever since it has long disappeared for billions of years the world has changed.
A young man who has faced a cruel fate wishes he could change what happened in his past life so that his twin sister didn't suffer so much before they were killed by those people who made their life living hell and took away their happiness so what if his inside a book? This world is truly real to him and he won't do anything but protect those around him. So he will do everything in his power to protect everyone even if it means to crossdress as a girl to protect his younger sister who never wanted to go to most powerful academy in the first place.