The Demon King's Successor

This story is about a high school student whose life takes an unexpected turn when The Demon King chose him to be his successor. The Demon Lord predicts his death and the destruction of Demon Realm when the war breaks out between demon realm and heavenly realm. Before the war breaks out The Demon King decides to send his powerful demons and other demons to human world to find their successor and when time comes they'll take over their body and use it to create new Demon Realm. The Gods realized The demon kings plan and decides to send their powerful angels and heavenly beasts to earth to find their own successor and fight against the new demon realm.