Highschool DxD: Savage Hyoudou.
They say that Ophis and Great Red are the only two Dragon Gods, but there are two others, more powerful and ancient than even them. In the Beginning of Earth's Mesozoic Era, two of the first ever Gods on the planet, the benevolent Skyranu, Dragon God of Life, Day and fertility, and Extirua, the Dragon God of Disaster, Night and Extinction, fought for eons until the end of the Cretaceous when the Meteor came, Skyranu decided to make an island sanctuary for the dinosaurs, the megafauna of the Cenozoic were also brought to the island while various races were also allowed to live in Skyranu's realm.
millions of years later, Issei was Neglect by the town of Kuoh in favor of his Sacred Gear bearing siblings and the ORC, while on a cruise, the girls, sure they hated the pervert, tried to save him from his father, who pushed him overboard, then out of pure luck, the boy landed on the Island that Kiba warned him not to go there, then Issei discovered what truly was on this undiscovered land, from prehistoric beasts to hostile humanoids, issei must survive this new environment, from his prison to maybe his new home.
