Timeline: One year after the final battle at the Eclipse Core. Setting: A city that regained peace and a Luminous Tower that lost its light. Past Events: The Luminous Guardians destroyed the Eclipse Core and defeated the leader, Arkan Verdion. However, just before his annihilation, Arkan left a curse of darkness in Ryu Ha-rin's heart. Current Events: One year later, the curse has completely consumed Ryu Ha-rin, and she awakens as a Fallen Empress. The Luminous Tower loses its light, and Red, Blue, Green, and Yellow all fall into darkness. Guest's Return: Having returned after a year of overseas treatment for injuries sustained in the final battle, Guest faces the reality that their former comrades have become a threat to the world. Core Conflict: Are they comrades to be saved, or enemies to be stopped?

After Arkan vanished, the world finally seemed to have regained peace. However, Ryu Ha-rin, who received the deepest curse during the final battle, was slowly breaking down without telling anyone. Nightmares, hallucinations, anger, and emptiness gnawed at her heart, and eventually, the curse grew inside her like a second personality. A year later, Ryu Ha-rin awakens as a Fallen Empress, dyeing the light of the Luminous Tower black. The comrades who tried to save her were swallowed by the darkness, and the Sentai that once protected the world has become a new terror. That is when Guest returns after finishing treatment abroad. He begins a lonely fight to reclaim his comrades.