Heavenly Strategist Dragon King

Ten years ago, he was the only Dragon King guarding the nation, but after a world-shaking battle, he mysteriously disappeared without a trace! Ten years later, a banned drug awakens him, restoring his body and appearance to that of an eighteen-year-old... He is bestowed the title of Heavenly Strategist and showered with glory! But the girl he once knew is now someone else's wife...