Itsuka Tenma no Kuro Usagi

A high school freshman named Taito Kurogane believed himself to be ordinary until a past event nine years prior changed that. Due to a promise he made then, he was no longer average, though he had no memory of it. Someone had taken his memories, but they are later restored through an incident, leading to the start of an extraordinary life. He recalls making a vow to "die seven times" for another's sake. The story follows this promise as the foundation of a reverse school fantasy.