Arb (アーブ Ābu) appears in Ultraman Mebius Gaiden: Hikari Saga SAGA 1: "Arb's Tragedy", and SAGA 3: "Return of Light".
Ultraman Mebius Gaiden: Hikari Saga
The Arb were a peaceful race of alien beings who lived on Planet Arb. The being (who would one day be known as Ultraman Hikari) visited their homeworld one day. He met and spoke with the Arb, who knew of his arrival, because of the prophecies made of the being known only as "Tsurugi." Hikari had been searching for the planet to study why it had never had a single internal conflict, and the Arb welcomed him as not only their guest, but their friend. A monster was predicted to attack and destroy the planet Arb in the prophecy of Tsurugi, called Bogar. Hikari wanted to meet this Tsurugi, as he may be able to teach him to fight. When he returned with his new Knight Brace, the prediction soon came true, as the space monster arrived on the planet, and began destroying all in her sight.
Hikari, having gained the Knight Brace's powers, was ready to fight Bogar. The Aab swarmed the beast, but she opened her wings and ate them in large gulps, until only a few remained. Hikari became enraged by this, and lept into battle against Bogar, using the new Knight Beam Blade, that he summoned out of the Knight Brace given to him by Ultraman King. Ultraman King warned him not to fight with such rage, as the power would overwhelm him. Hikari angrily ignored the warnings, and fought fiercely, but Bogar overpowered him easily. After Hikari managed to get in only one shot, Bogar decided to retreat, for now, and disappeared into thin air. After the battle, Hikari wallowed in what was left of Planet Arb. He was now furious with himself, and struck the ground several times in anger. Just then, the usually kind spirits of the dead Arb appeared, and they threw themselves onto Hikari's body, merging with him, and transforming him the powerful being known as Hunter Knight Tsurugi!
Return of Light
While Hikari was traveling through space, on his way back to Earth, he noticed an Ultra Sign, saying "I'm waiting for you on Planet Arb- Mebius." Wanting to find out what Mebius was doing on Arb, Hikari went to the planet. There, as he searched for Mebius, he knelt down, and touched the soil of the planet he failed to save. Suddenly, a blast of energy flew right past his face! Turning to his side, it was Ultraman Mebius! Mebius suddenly attacked Hikari, but Hikari wasn't afraid to fight back, knowing it was an imposter. He demanded the faker's real identity. Instead, the Mebius being took on the form of Hikari's old shelf; Hunter Knight Tsurugi! The fake told Hikari of his plan to go to Earth disguised as him, and destroy everything in his name! The two engaged in battle again, with the fake winning, claiming he had the power that comes from revenge and pure rage. He also said if Hikari admitted defeat, he'd have to become the imposter's slave, but he would spare his life. Hikari refused, saying he wanted to protect the precious lives that were at risk. The imposter just laughed, and decided to reveal his real face; Alien Babarue!
Engaging in battle yet again, Babarue used his freezing breath to freeze Hikari within a large block of ice. Babarue offered Hikari one last chance to be his slave and live on, but Hikari still denied him. Babarue finally decided to leave, and he started skipping merrily away. Then, the spirit of the Arb spoke to Hikari, and reminded him of the good times he shared with them. They also granted him a true power, and with it, he broke free of the ice block, and transformed into what appeared to be Tsurugi! But instead of hatred and rage, the energy in his body was pure, and clean. Hikari had been given the Armor of the Hero which appeared identical to the Armor of Revenge he once wore, the Armor of the Hero was the true form of Armor of Revenge, it gave him the power he needed to easily defeat Babarue. Beaten, Babarue claimed he'd one day kill both Hikari and Mebius. Then, he slammed the ground and disappeared in a cloud of smoke, without a trace. Hikari left the planet, heading to Earth but left knowing that one day the planet Arb would be beautiful and full of life again.
- Height: Unknown
- Weight: Unknown
- Origin: Planet Arb
- Powers and Weapons
- Power Surge: Each individual Arb can charge their tiny bodies with energy and can shock foes with their touch.
- Astral Form: While on their own, the Arb resemble crystals, they can group together into a vaguely-humanoid figure.
- Flight: The Arb can fly through the air at moderate speeds.
- Telepathy: The Arb can speak to others through telepathy.
- Intelligent: Ultraman Hikari theorized that the Arb are some of the most intelligent creatures.
- Merge: When the Arb died, they merged with Ultraman Hikari and formed the Armor of Revenge. However, this causes Hikari unintentionally to be fueled with rage and anger energies in him.
- Pure Energy Transfer: After Hikari was defeated by Alien Babarue, Arb transferred their energy to Hikari and allow him to transform into the Armor of the Hero. This energy fueled Hikari is clean and pure.