|“||It doesn't look like there's anyone who can see through my Imitation Transformation Magic. Well, whom could I have been imitating?||”|
— To Audience in Three-Leaf Salute
Rhya is a young man with a red tattoo on his left cheek and patches of white hair in his messy black hair. Under his hair hides a third eye in the middle of his forehead.
As an elf, he has messy, white hair and a more angled jaw.
Once the Reincarnation Magic is removed, Rhya's appearance resembles that of his human host's body: black hair with white patches and black irises. However, his ears remain pointed and his tattoo disappears.
Rhya has a laid back personality and is rather lazy, but is quick to fight, albeit unwillingly, to protect an ally. Seemingly the calmest of the Third Eye, he cares deeply for Patolli, fleeing a fight to re-seal his power, and is rather worried for him.
Living up to his title as the "Disloyal", Rhya can tell one is being deceptive. In fact, this trait allowed him to realize that were inconsistencies in the Elf genocide and later seeing Asta's ideals of a world of mutual understanding to be genuine. But in both cases, though he believes things would had been different if there more humans like Asta and the first Magic Emperor, Rhya remains undeterred from his goals of being reunited with his kin at any cost.
One day, Rhya shows Licht his grimoire and tells him about his Imitation Magic, joking that it is empty like himself. Licht instead remarks that Rhya and his magic are kind. The day before Licht's wedding, Rhya is late in attending a meal with the other elves. After the wedding is attacked and the elves are massacred,
Rhya and the rest of the Third Eye come to Patolli's aid after he was defeated by the Black Bulls, appearing from Rhya's copied Spatial Magic. In a flash of light, Rhya approaches Yami Sukehiro and touches the captain's grimoire, commenting on its strange design. Yami swings at him with Dark Cloaked Avidya Slash and Rhya dodges but is still hit. Complaining that this is why he does not like getting involved, he heals his arm. Patolli asks for his allies' forgiveness, to which Rhya asks why Patolli always tries to take on everything by himself. Patolli introduces the trio as the Third Eye and says that their powers are greater than his. When Finral Roulacase calls their strength a bluff, Rhya proves it by attacking Yami with a copied Dark Cloaked Avidya Slash.
The Third Eye's stream of attacks forces Yami to focus on defending his team, and with the captain overwhelmed, the trio attack simultaneously. However, their attacks are countered by the arrival of three Magic Knight Captains: Jack the Ripper, Nozel Silva, and Charlotte Roselei. Rhya decides to continue fighting for Patolli. Charging at Charlotte, Rhya says that if he wins he will takes her to a sweet bar, to which Charlotte replies that he will be going alone. Rhya battles against Charlotte before being alerted to Asta landing a blow on Patolli that removed the seal on their leader's mana. Rhya helps the other Third Eye members quickly seal Patolli's erupting mana before grabbing Valtos as the group decide to withdraw to take care of their wounded.
A few days later in the Magic Knights headquarters, Rhya attends a meeting disguised as William Vangeance. Once the meeting has concluded, Rhya removes his disguise and compliments himself, saying that no one is going to get suspicious for a while.
Months later, Rhya awakens after having dreams of his past with the Elf Tribe. After the Royal Knights attack the floating dungeon, Rhya opens his third eye in preparation for the fight. He disguises himself as Asta and sneaks into Mereoleona Vermillion's team. Both plead that they are the real Asta, so Mereoleona burns both of them. The real Asta survives due to his Anti Magic while Rhya is greatly hurt and has to put out the flames and heal himself. He compliments her beauty but dislikes her being a royal. He then attacks with copied Dark Magic, but she burns away his spell before dashing forward and engulfing him in flames.
Rhya retreats and heals himself before launching several swords of light, but Mereoleona destroys them and closes the distance again. He attacks with a variety of spells, all of which she counters with punches, so he pulls out a copy of the Demon-Slayer Sword. However, she punches it too, breaking it, and pummels him with a flurry of punches.
Overwhelmed by her attacks, Rhya resorts to a self-destructive spell, but Asta cuts through the cloud of mana with his Anti Magic. He then punches Rhya and yells at him for trying to throw his own life away. When Asta talks about his hope for a world where everyone can accept and understand each other, Rhya is reminded of Licht long ago but admits that it is too late to stop them. After Patolli places the last magic stone, Rhya begins glowing and declares that the time of humans is over.
Upon being fully resurrected, Rhya immediately attacks the Royal Knights with two different elements simultaneously. Mereoleona defends her teammates and counterattacks but Rhya evades. The elf fires multiple light beams through Myriad Black and manages to injure both Mereoleona and Asta. Their battle is interrupted when Lira, who is in Rill Boismortier's body, crashes through the ceiling. Rhya joins Lira atop the Four-Headed Lindworm and watches Lira fight the Knights. In the battle, Zora tries to blind and paralyze the elves, providing Asta an opening to free Rill from possession, but Rhya explains that the spell is complete and cannot be nullified by Anti Magic.
Three more possessed Knights then arrive, and Rhya and Lira both begin charging large magic blasts. After she throws Asta and Zora out of the room, Mereoleona counters the blasts and challenges the five elves by herself. The elf in Puli Angel provides Angel Wings to Rhya and the five elves attack Mereoleona in series. Lira paints a giant that is too large for Mereoleona to burn away, and when she tries to dodge the punch, Rhya warps the fist to a different angle, enabling it to connect and knock her down. When Mereoleona is distracted by escaping Rossa's Variable Hardness Prison, Rhya ambushes and slashes her while the other elves rain more feathers down on her. However, she survives and attacks Rhya.
Mereoleona unleashes her strongest attack, but the elves survive with minor injuries at the cost of most of their mana. Seeing that Mereoleona is also still alive, the elves combine their magic for one final attack to finish her off. However, Zora and Asta arrive and, using Zora's counter traps, quadruple the power of Elemental Quintet and reflect it back at the elves. The spell passes overhead and detonates behind the elves, allowing for the Knights to escape.
Refusing to let Asta escape, Rhya catches up to the three Knights, grabs Asta, and pulls him into a portal. Rhya drops him in the central room of the dungeon, where Licht waits. While the possessed Klaus Lunettes and Hamon Caseus fight Asta and Yuno, Rhya ponders why Yuno is in control and why Licht is unresponsive. When the two young Knights defeat the two elves, Rhya is surprised by the boys' strength and by Licht finally taking action. Rhya relaxes as he watches Licht easily take on the two boys; however, he worries when Yuno uses Mana Zone to create an opening for Asta and him to attack Licht from point-blank range. Licht deflects their attack and blasts the three Knights out of the dungeon. Rhya questions why Licht did not keep his grimoire and swords, to which Licht responds that they are no longer his.
Ado then joins Rhya and Licht and creates doors for the other elves in the dungeon into the central room. The dungeon is then steered toward the Clover Kingdom and their revived brethren. Rhya sends Ado and some others to find Yuno and retrieve the magic stone. Within the dungeon, Vetto and Fana are reincarnated into artificial bodies, and Rhya arrives to greet them. After the two dress, Rhya takes them to get new grimoires.
Once the dungeon reaches the Royal Capital, Rhya goes to greet Patolli, Drowa, and Eclat who have arrived in the dungeon. Rhya and Patolli briefly discuss Licht, the remaining elves, and the final magic stone. The Apostles of Sephirah assemble atop of the floating dungeon and summon the Shadow Palace. Afterward, Rhya and most of the elves fly through the gate.
When an eleventh chamber appears in the Shadow Palace, Rhya, Patolli, and Ronne gather in the room and wait for Yuno to arrive with the final magic stone. Patolli and Rhya unleash a doubled array of light swords, but Yuno dances around the swords and hits the two elves with Spirit Storms. Rhya is impressed with how much Yuno has improved his human and elven abilities. When Ronne manages to steal the stone, Rhya realizes something is amiss and questions the elf's true identity. Instead of answering, Ronne blasts a hole through Rhya's stomach. Rhya, thinking of how he hid his suspicions over their massacre from the others while realizing Ronne only just joined them, collapses with Patolli healing him.
When the possessed Ronne summons a devil from the underworld, Patolli's attempted attack is reflected at him and Rhya, but they are saved when Yuno pulls the two to safety. The devil pulls Patolli away from healing Rhya, who watches helplessly as the devil tortures Patolli and fights Asta and Yuno. When Yuno's Spirit Dive develops further, Rhya questions if Licht's child has awakened. Rhya is distraught as Patolli's grimoire and body are corrupted by despair.
After Nozel defeats Patolli, Mimosa takes over healing Rhya, who notices a similarity to Tetia. He is amazed when Asta manages to break Patolli out of despair. The devil's magic pours down from the topmost chamber and almost swallows Rhya and Mimosa, but Asta throws them to safety. Nozel and Mimosa take Rhya and Ronne on their quest to bring together the other Magic Knights. As they are travelling, Licht draws on the elves' magic to help power a spell to destroy the devil. The devil survives and floods the Shadow Palace with more of his magic, so Licht and Lemiel send out protective auras to the elves. After the devil is defeated, the magic does not disappear whereas the protective light wanes. Valtos saves the elves and Magic Knights and warps them up to the topmost chamber.
- Imitation Magic: Rhya uses this magic attribute to copy other magic. He needs to touch the grimoire of an individual in order to copy the spells. He has copied several types of magic, and his copied spells are able to match those of the original owners. However, he cannot copy Anti Magic and is limited in how many different types of magic that he can use at one time.
- Transformation Magic: Rhya uses this form of magic to take the form of another human being. Initially he is unable to use other spells while transformed; however, his completed reincarnation allows him to use at least two types of magic at once.
- Compound Magic: Rhya uses this form of magic to combine multiple different spells to create a single, more powerful spell.
- Immense Speed: Using Light Magic copied from Patolli, Rhya is able to cross large distances in an instant and can dodge point-blank attacks with minimal damage.
- Immense Durability: Rhya's overflowing mana grants him great physical resistance, as shown when he survives Mereoleona's ultimate attack relatively unscathed.
- Immense Magic Power: As an elf and an Apostle of Sephirah, Rhya possesses an immense amount of magic power and is stated to have greater battle prowess than Patolli. He is able to fight on par with a Magic Knight Captain despite holding back severely, and alongside the other Third Eye's, he is stated to have mana control and reserves that are leagues beyond the Magic Knight Captains of the Clover Kingdom.
- Grimoire: Rhya possesses a three-leaf clover grimoire, which is able to copy and maintain the spells of other grimoires.
- Yami Sukehiro vs. Rhya, Vetto, and Fana: Interrupted
- Jack the Ripper, Nozel Silva, and Charlotte Roselei vs. Rhya, Vetto, and Fana: Interrupted
- Mereoleona Vermillion vs. Rhya: Interrupted
- Mereoleona Vermillion vs. Five Elves: Interrupted
- "It doesn't look like there's anyone who can see through my Imitation Transformation Magic. Well, whom could I have been imitating?" 「ウチの模倣変身魔法を見破れるヤツはいないね...! さてウチは誰に化けてたでしょーか "Uchi no mohō henshin mahō o miyabureru yatsu wa inai ne...! Sate uchi wa dare ni bake teta deshōka"」
- The design for Rhya is based on Japanese actor Hirofumi Arai, after he personally asked Yūki Tabata during a segment of Jump Undercover Mission Police. Hirofumi later became the voice actor for the character.
- Rhya's Japanese name, Raia, is an anagram for Arai.
- Following Arai's arrest and indictment for sexual assault, he was replaced by Masakazu Morita as the voice of Rhya.
- Rhya ranked #28 in the first popularity poll, #25 in the second, and #21 in the third.
- Rhya's grimoire design is the background for Volume 16's cover.
- Rhya's favorite things are his fellow elves, banquets, and basking in the sun.
- Rhya's position on the sephirot corresponds to Binah ("Understanding").