Dragon' s Vow

Ancient Black Dragon King Kael is betrayed by his brother White Dragon King Draco, his physical body shattered, leaving only a remnant soul that reincarnates as an F-rank little black dragon; contracted by the kind-hearted girl Celia, he unlocks the Devour Evolution System and gradually restores his power by absorbing monsters and elemental crystals. Kael crushes the arrogant noble scions who mock Celia, ventures into major secret realms to subdue the Black Dragon's former subordinates, gathers nine of the Ten Dragon Sovereign Blades, and befriends Elizabeth, who possesses a Pure Spirit Body, and Alice, a descendant of the dragon clan. As White Dragon King Draco continuously dispatches the White Dragon Guards to hunt them down, and the academy villain Blake and noble Thorvald set up schemes one after another to harm them, Kael collects the Thousand Spirit Stones in the Sky Vault Secret Realm, masters the Dragon Emperor's Might, completes the full Ten-Blade Sword Formation, and finally engages Draco in a decisive battle above the Supreme Academy, sealing his sworn enemy before guarding the peace between humans and dragons alongside Celia and Elizabeth and ruling over the Ten Thousand Dragon Territories.