An ancient Titan is sealed within my body

Elias, son of the God-King, had his divine power constantly drained by his adoptive family and was also ostracized and plotted against by his foster brother, Sevien. When his village was attacked by a dragon, Elias awakened his Titan powers, but Sevien stole his dragon-slaying credit. During the knight selection, he was repeatedly framed but was protected by Princess Ariadne. Later, Sevien betrayed his country by joining the Abyss and conquered the capital. Elias, having fused with Titan power, slew the villain and married the princess. Finally, he went to war once more to aid Mount Olympus, which was besieged by demons.