The Triplets' Final Regret Ending Explained: Full Plot Summary & Episode Spoilers

Following the tragic loss of her parents, young half-blood Elisa Carter is brought into the lavish estate of Catherine Lockhart, principal of Cross Academy. Catherine's three sons, Jacob, Oliver, and Nash, adore Elisa, shielding her from school bullies and swearing that one day she will wed one of them. Because she dreams of remaining by their side forever, Elisa intends to undergo human purification upon turning eighteen.

Everything collapses when Amber, the daughter of a household maid, arrives at the mansion. Envious of Elisa's status, Amber fabricates an incident where Elisa caught her stealing money, cleverly flipping the blame onto Elisa. Without bothering to check any security cameras, the gullible triplets instantly accept Amber's tale, stripping Elisa of their warmth and publicly bestowing their championship hockey jersey upon Amber instead.

As the deadline for her racial decision nears, the mistreatment by the triplets intensifies. The brothers clear Elisa's personal cushions from their vehicle to accommodate Amber, ignore Elisa's eighteenth birthday, and even burn a symbolic protective handkerchief they had given her years earlier after Amber claims Elisa assaulted her.

Heartbroken and unwilling to suffer further degradation, Elisa informs Catherine of her wish to transfer to Cross Academy's nocturnal division and become a vampire. Catherine respects the decision and honors an ancient pact that betroths Elisa to the vampire royal family. Meanwhile, the triplets assume Elisa's talk of transferring is merely a petulant bluff, escalating their cruelty by striking her when Amber fakes another fall.

During a confrontation near the school stairs, Amber pulls Elisa into a fall. Although Elisa is already injured and in pain, the brothers rush exclusively to coddle Amber, leaving Elisa bruised and bleeding on the floor. At her lowest point, Vampire Prince Cain Trueblood intervenes, scooping Elisa into his arms and taking her under his complete protection.

In the night school, Elisa is welcomed warmly rather than treated like an outcast. Unlike her former foster brothers, Cain never demands that Elisa prove herself or earn his loyalty. Under Cain's devotion and care, Elisa completes her transition, preparing for her formal awakening into the vampire race.

Panicking after seeing Elisa accompanied by Vampire Prince Cain, the triplets finally remember the estate's CCTV system and review the old footage. Confronted with recorded proof that Amber staged every theft and attack, the brothers are crushed by guilt and race to win Elisa back, desperately kneeling and pleading for her forgiveness.

Elisa remains entirely unmoved by their tardy remorse. During her coming-of-age ceremony, Cain orders his guards to arrest the triplets and locks Amber in a dungeon. Elisa successfully awakens the rare Primordial's Wings, and Cain announces their upcoming royal marriage, leaving her former tormentors to face justice while Elisa steps into her future as vampire queen.