High School DxD: Return of the Crimson Dragon Emperor Novel

Hyoudou Issei, Kuoh Academy's notorious Red Dragon Emperor, mysteriously vanished and was presumed dead. In reality, he was transported to another world filled with magic, monsters, and demon lords. Over three years, he survived, trained relentlessly, and grew powerful enough to challenge gods and conquer kingdoms. Now he returns—transformed but unchanged in his perverted nature. This older Issei possesses mastered powers and a sharpened mind, yet still screams about attractive women, only now he can destroy mountains while doing so. The devils, angels, and fallen angels have no idea what awaits them. His old friends face uncertainty about whether to welcome, fight, or flee from him. Those who doubted him should beware, as his Dress Break ability has evolved considerably. A stronger, more powerful, and increasingly perverted Red Dragon Emperor has returned to Kuoh, bringing chaos, comedy, romance, and overwhelming strength in his wake.