Years earlier, Leon, a humble male merfolk, shares an unexpected night with Areno, the powerful Merfolk King, an encounter that eventually leads to the birth of their son, Finn. Unaware of his existence, Areno remains separated from his child until six years later, when he discovers the truth and sets out to find them. Meanwhile, struggling to afford treatment for Finn's illness, Leon secures a position as a palace attendant, unknowingly bringing himself face-to-face with the king once again. Areno instantly recognizes Leon as his destined partner and refuses to give up on winning him back. However, their chance at happiness is threatened by Lilith, a jealous noblewoman determined to make Leon and Finn suffer. As hidden secrets unravel, Leon discovers that he is actually the missing heir of a prestigious family. With the enemies finally exposed and punished, Leon and Finn reclaim their rightful place among their loved ones, opening a new chapter filled with love, family, and happiness alongside Areno.