To Aru Majutsu de Gakuen Tengoku by DORILL

The main character fainted, and when he woke up, he was in the hospital.
Nearby was a girl named Index, and behind her, one by one
on his way, he met new girls whom he could not remember.
Has something terrible happened, since his mind refuses to tell about it?
In this city of magic, the hero has a lot to find out.
The beauties will involve him in more than one alteration.