The Hollow (虚無, Kyomu?, lit. Nihility) is the main antagonist force of Final Fantasy Brave Exvius Season Three. It is a mysterious, unknown entity that appears in multiple worlds with the intention of depriving them of both living and immaterial things. The Hollow and its proxies are protected by the Hollow Keepers.
The Hollow is analogous to the Final Fantasy series's The Void, a space that is both consuming matter and worlds into nothingness, and also exists as a realm of formation and connective tissue between different worlds.
The Hollow is a force of nothingness controlled and embodied by the Will of Oblivion, which stands in opposition to the Will of Light, with the two existing in balance. The Hollow appears as a black and white revolving wormhole. The Will of Oblivion appears as a fully darkened crystal, irradiating starkly blank light with no sign of life.
The Will of Oblivion is nihility incarnate. It seeks only to destroy and consume everything into nothingness for no reason other than being an embodiment of emptiness. The Will of Oblivion is manipulative, promising salvation to Chorale's crew to convince them of serving the Hollow as a means of following a bigger picture, but ultimately using them as pawns and cruelly disposing them once the Hollow's true servants awakened.
Despite being a force of nothingness meant to preserve balance through a mutual harmony of life and destruction, the Hollow is malignant in nature. Those that come under its influence have a drastic change of personality, exhibiting extreme nihilism, sadistic tendencies, and mania.
The Hollow is a force of nothingness the Will of Oblivion controls, standing in opposition to the Will of Light. While the Hollow causes destruction, the light brings forth life, and were the light be left unchecked, the world would collapse due to the excess of life. If the Hollow were left on its own, everything would be consumed by eternal nothingness. To further preserve this balance and keep one another restrained, the two Wills created two beings, the sisters Fina and Dark Fina, to maintain stability.
Due to the events in Paladia and the battle against Vlad, Dark Fina disappeared as a result of using her powers to travel through time to give Rain, Lasswell and the Sworn Six of Paladia the means to defeat Vlad. This disrupted the balance and the Hollow went out of control and ravaged the worlds connected to the Farplane, stripping them of things both material and immaterial. A silver fog spread through wormholes, which is the conduit used to steal from the worlds.
In the Fortified City of Berga, a playful Rinora found himself lost in the ruins of a forest where he stumbled upon the Will of Oblivion, awakening it and bonding with it. Under the Will of Oblivion's influence Rinora sought recruits for an organization known as the Hollow Keepers to defend the Hollow and allow it to cause havoc and spread. The first recruited for this endeavor was Chorale who was tasked with finding other members. All of them joined for largely personal reasons, but most joined believing that worlds are better off without whatever the Hollow absorbs.
The Hollow and the Hollow Keepers are opposed by a group dubbed by the latter as Hollow Breakers, individuals chosen as the champions of each world tasked with defending them from the Hollow's influence. They travel in the Farplane Express to reach the worlds connected to the Farplane and restore what the worlds lost.
The Hollow attacked Berga by stripping its inhabitants of the ability to move. Bruce and his wife, Ella, met the now possessed Rinora trying to kill them. Ella died in an accidental blast, while Bruce was forced to fight his brainwashed son. Summoning the Esper Doomtrain, he knocked Rinora off a cliff. Bruce tried to finish Rinora off, but the latter suffered from amnesia due to the fall. The Will of the Light appeared before Bruce explaining that Rinora is bonded with the Will of Oblivion and explainwed the Hollow's threat. Bruce wondersed if closing the wormholes would restore Rinora, to which the Will responded it might restore his memories but not purge him of the Hollow's influence. Not seeking to murder his amnesiac son, Bruce accepted the Will of Light's request to travel the worlds and close the wormholes.
One day Fina, now living in Grandshelt, is cooking for Physalis, now a member of the Knights of Grandshelt, and wonders about her future. Her powers are weakening, Fina believing it a result of her missing counterpart. The Will of the Light appears before her and a voice pleads her for help to save the world. Following Rain and Lasswell's example, Fina decides to help the voice, touching the Crystal and transforming into a Blue Mage.
Fina is transported to the Farplane where a station appears before her along with the Farplane Express. The conductor, Rinora, takes her with him as her name appears on the list of passengers. As Fina boards Rinora explains that the train's passengers are meant to restore that which the worlds lost.
Fina is joined by fellow passenger Bruce and the two travel to Wohlstok. As Fina and Bruce make their acquaintance, Bruce reveals he has cast away his past, whereas Fina has no memory of her own. As the two travel to Silent Village Corte, they find its citizens under attack by monsters, but the citizens do not react, forcing Fina and Bruce to defend them. Bruce explains the Hollow has taken people's emotions away, thus depriving them of fear. The Hollow manifests through a wormhole, and if it is closed, the Hollow will be repelled, restoring the world to normalcy.
Fina and Bruce hear a scream and rush to encounter a young woman called Daisy who has retained her emotions and fights to protect a pair of children from monsters, but who refuse to escape due to their inability to feel. Fina and Bruce help Daisy repel the monsters. During their encounters they meet Mazurka, a Hollow Keeper who tries to convince them of the futility of restoring emotions. Daisy requests their aid in setting up a theater, which fails. As they try to close a wormhole Mazurka stands in their way, but is defeated, and they leave to deal with the wormhole's true guardian, the Voa Wohlstok a Hollow Dragon. As they defeat the monster, Fina acquires new powers due to her ability to learn as a Blue Mage. A floating baby appears before them, full of magic power, whose name is Roca and whom they are tasked to bring to the Will of Light.
Fina and her party encounter Milieta, a friend of Daisy's who has lost her emotions and whom the latter tries to convince to perform together. Mazurka appears once more and reveals her past as a bullied girl, which is why she wants people to remain emotionless. Daisy and Milieta perform "Of Sword and Shield" restoring Milieta's emotions. Now chasing after a second wormhole, the party defeats Mazurka who is left on despair, but whom Fina offers a hand of friendship. Mazurka is distraught and leaves wishing Fina to not die. The party closes the second wormhole returning Wohlstok to normalcy.
As the party is bound to live for the next world, Daisy decides to go with them as a power is unlocked inside her, so she is allowed to accompany them.