Legend says that a mermaid with the "Ultimate Heart Scale" can purify anything. Callista, a wandering mermaid, used the power of her Heart Scale to save the gravely injured Tide Prince Caspian in a storm. The two fell in love, and Caspian swore to marry her and protect her for life. However, at their wedding, Caspian's childhood friend Lilia suddenly suffered a relapse of the "Abyssal Poison." Under moral coercion and pressure from the royal family, Caspian personally tore the Heart Scale from Callista's chest to save Lilia. Completely broken-hearted, Callista, in Caspian's gaze of regret, plunged into the Abyssal Tides—the most dangerous forbidden zone of the seven seas. To sever her past forever, Callista drank the Waters of Forgetfulness, erasing the scumbag from her very soul. Everyone assumed she had perished, but Callista awakened the Platinum Bloodline, regrew her tail, and awakened Astaroth, the Abyssal Dragon who had been sealed for a century. This demon god, the pinnacle of power and savage cruelty, willingly sheathed his fangs and became her most loyal, obsessively devoted knight, escorting her back in glory. At the Return Ceremony, a regret-filled Caspian and the scheming Lilia came to pay homage. When they looked up, they were shocked to find that the unattainable, supremely powerful princess before them was the "commoner trash" they had driven to death. Facing Caspian's tail-severing plea for forgiveness, Callista only offered cold mockery. Facing the moral coercion of the Seven Seas Alliance, she protected her knight with domineering strength, willing to defy the entire world rather than surrender the dragon who saved her. In the end, the hypocritical Tide Royal Family was reduced to slum dwellers. Callista, with the Abyssal Dragon's ultimate devotion offering the entire Abyss as her "dowry," merged the Seven Seas and the Abyss, and was crowned the one and only Queen of the Ocean World.
