Au, Highschool DxD universe.

Izuku Midoriya had been bullied through out school, very few friends, if you can even call those that pity you friends. One day Inko Midoriya, Izuku's mother learned this, and chose to move and transfer Izuku to another school.

Kuoh Academy, a School is Kuoh Town. Once a female only Boarding school, now a Co-ed. Within its walls are two groups, the Occult Research Club, Or ORC, and the Student Council. They all may seem like your typical popular highschool students, but in reality they are devil, both Pureblood and reincarnated. One of the groups leaders, Rias Gremory, has a desperate need to gain powerful peerage members, as her freedom may be on the line of a Rating Game.

Little does anyone know, is that Izuku is not a pure blooded human, but a desendant of Demi-gods, on both sides of his family. His Mother a desendant of Zeus(on her fathers side) and persephone(on her mother's side), and his father, who has long sense passed away, a desendant of Hephestus. But it doesn't stop there, Izuku also has a sacred Gear, albeit a simple Twice Critical(Chest plate, Mouth Guard(like the smile face mask from his hero suit), gauntlet Braces, and Grieves), but over time, with the help of powerful emotions, even the most low tier of Sacred Gears become the stuff of legends.

So Izuku has Demi-god ancestry and a twice critical, but guess what, he ain't op, not yet at least. At birth, he had blood locks, a form of sealing on ones inherited powers, place on his Deity genes, keeping his Demi-god powers and identity hidden. However the power from Persephone leaks out making Izuku the Cinnamon roll everyone loves, this allows him to emotionally and psychologically reach out to people, and attract attention. However, Izuku can't be turned into a Devil because of the Blood lock.

The inherited power of Zeus will leak out during his fight with Riser.

Inko has two, untouched, unmodified, and uncorrupted Excalibur core shards, which means they haven't lost the Fae enchantments, and haven't been weakened by holy metals and element. They are the power of Purification and Absorption. During the Excalibur Arc, Inko Reveals her and Izuku's true identitys, and places the Excalibur Core Shards into Izuku, and his Sacred Gear, which allows him to link with the spirit of Artoria Pendragon and manifest a, albeit weaker, copy of Excalibur, which cuts through the combined fragments.