Honestly, This Dog Thinks of Nothing but His Grandchild: The Demon King Living A Dog's Life Has Unfinished Business

The domination by the Demon King's Army—known as the Demonic Invasion—spanned several hundred years, during which countless heroes were helplessly struck down by the Demon King...! However, the hero Terios, hailed as the Last Hope, finally slayed the Demon King. The world attained peace, and the hero Terios vanished somewhere――. But the Demon King, said to be dead, is miraculously revived! As a dog...!?