Seirei Gensouki - Konna Sekai de Deaeta Kimi ni (MINAZUKI Futago)

Amakawa Haruto is a young man who died before reuniting with his childhood friend who disappeared five years ago. Rio is a boy living in the slums who wants revenge for his mother, murdered in front of him when he was five years old.

Earth and another world. Two people with completely different backgrounds and values. For some reason, the memories and personality of Haruto who should've died are resurrected in Rio's body. As the two are confused over their memories and personalities fusing together, Rio (Haruto) decides to live in this new world.

Along with Haruto's memories Rio awakens an unknown "special power", and it seems that if he manages to use it well he can live a better life. But before that, Rio encounters a kidnapping that turns out to involve two princesses of the Bertram Kingdom that he lives in.

After saving the princesses Rio is given a scholarship to the Royal Academy, a school for the rich and powerful. Being a poor orphan in a school full of nobles turns out to be an extremely detestable situation to be in.