Seirei Gensouki
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 who was 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 is 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 uses it well, he can live a better life. But before that, Rio encountered a kidnapping that turns out to involve two princesses of the Bertram Kingdom that he lives in.
Note: This is a relaunch of the now discontinued alternate story: Seirei Gensouki ~Konna Sekai de Deaeta Kimi ni~