Seirei Gensouki

Rio, an orphan living in the slums, had his soul transmigrated by a Japanese university student named 'Amakawa Haruto' when he was seven years old. When he realized it, he had already been reincarnated into a different world with swords and magic. Using powerful magic he didn't remember, Rio solved the abduction of a girl, and his contribution was evaluated as a special case for a non-noble child, allowing him to enroll in the academy for the distinguished!?