A hundred years ago, Thalen the Sea God saved the Maris Sea from monsters and a prophesied tsunami. Kael, saved by him, received an Oath Emblem that could grant any wish. A century later, the sea citadel faces ruin. Dying Kael summons Thalen to form a three-year soul bond with his granddaughter Serena to protect their clan. Thalen hides his divine identity, marries into the family as a blacksmith, and silently sustains the Sea Barrier—but Serena sees him as a disgrace. When noble Lord Cedric returns, he steals Thalen's achievements, frames him for treason, and claims credit. Blindly believing Cedric, Serena demands the bond be broken. Thalen agrees without protest and withdraws his power. The divine runes on the barrier fade—and the apocalyptic tsunami finally arrives, as the whole truth is about to break.