High School DXD: Issei the king of Gracias

Once upon of time it was an ancient civilization that worship the True God. God was pleased with them and granted them Grace, but not the gift of the divine favor in the salvation of sinners. No, this Grace had Infinite possibilities, it was the ability to manipulate nothing into something, or in short, the void. User with Grace are able to manipulate the 7 basic elements into their ultimate form. God decided to hide these people from the world, fearing that other human, or devils, and fallen angel's outside of the world will corrupt them or destroy them. So, he created a dimension similar to earth. These people were known as the Gracias. Issei Hyoudou or Issaac de tenebris caelum, was the prince of the Gracias, but one day an ancient evil awakened killing his family, and slaughter halve of his people. Issei memories were wiped, he was adopted by normal Japanese family.
Summary might change, also this story will have a lot of non-canon events so be prepared.

If you guys don't like the sacred gear let me know!