Grigio

Grigio appeared in 2018 TV series called Ultraman R/B. Grigio (グルジオ Gurujio) is a skeleton-like kaiju that debuted in Ultraman R/B. The first to appear is Grigio Bone (グルジオボーン Gurujio Bōn), which evolved into stronger variants later in the series.

In the past, three warriors from Planet O-50 were sent to defeat Reugosite, a planet-eating monster that destroyed everything in its path. The three warriors fought Reugosite in space, but were overcome by its power and they crash landed onto Earth. The two Ultramen disappeared and left behind was their sister, Saki Mitsurugi. Landing on Earth, Grigio Bone became a mythical monster featured in legends of Ayaka City, crashing to the Earth in a meteorite known as the Ayaka Star, along with two giants of light, 1300 years ago. It is said that people attacked him, but Grigio Bone swallowed them whole. He was given the name Grigio-sama (偶龍爾王様 Gurujio-Sama) by the locals, and Ayaka City was named after the incident. As revealed by Saki, the legend is proven to be false.

In the present, Grigio Bone was summoned by the power of a Kaiju Crystal by Makoto Aizen. First spotted by a couple taking photos, the footage of him was dismissed by Katsumi as CGI until Isami revealed his device had detected the monster's activity as well.

Grigio Bone then reappeared the next day when he emerged from a building and decided to go on a rampage after spotting Katsumi Minato and Isami Minato looking at him. The two brothers then went into a park where they decided to distract the kaiju to save a young boy named Kiwamu and just as they were about to be burned to death, the two brothers were given the R/B Gyro and Crystals. Katsumi and Isami then transformed into Ultraman Rosso and Blu respectively, fighting for the first time as an Ultra.

A fierce battle began in Ayaka City, with Grigio Bone fighting against Rosso and Blu who were seemingly inexperienced in battle. Blu made the first move, but Grigio Bone dodged his Jumping Kick easily and threw him back at Rosso. The kaiju then accelerated at the duo, but Rosso stopped him with his Flame Bullet and Blu used his Water Jet for the first time as well. As the two Ultramen and kaiju fought on, Rosso pulled up a tree from the ground and used it against the kaiju but the kaiju then caught it in his mouth and used Rosso as a shield against Blu's kick. Grigio Bone then unleashed his Bone Breathter on the brothers.

After a discussion, Rosso and Blu decided to switch R/B Crystals and for the first time, switched forms as well. Rosso used his Aqua Mirror Wall to block Grigio Bone's Bone Breathter and while they were fighting, Blu launched his Fire Bullets at the kaiju and, inadvertently, his own brother, causing the two of them to argue leading to an awkward moment with Grigio Bone which lasted until the kaiju scared them with his roar.

Afterwards, the two brothers worked together in combat, and even with their Color Timers flashing after attacking the kaiju with their W (Double) Kick, they didn't let up as they grabbed Grigio Bone, knocked him down, then swung him around with their Ultra Swing. The two Ultramen then encased Grigio Bone in a Splash Bomb and sent him flying with the Flame Equilix. In the end, Rosso and Blu switched back to their original forms and struck down Grigio Bone with the brothers' Flame Sphere Shoot and Aqua Stream and the kaiju exploded in the process and Makoto reclaimed the kaiju's Kaiju Crystal in the aftermath.

This wasn't the end of Grigio Bone, however, as Makoto transformed into Grigio once again and went on a rampage. Isami planned on taking on Grigio bone alone but for some reason, he couldn't transform into Blu. Even Grigio seemed confused by this revelation. Just as the kaiju was about to fry Isami, Ultraman Rosso interfered with his Flying Kick. While the two brothers were fighting, Grigio tried to get Rosso to fight him again, but when Rosso pushed him away, Grigio slapped him so hard, it left a mark. Embarrassed, Makoto reverted back to his human form.

After finding out that Isami couldn't transform because he got scared of becoming Ultraman after almost killing Kaoru, Makoto got flustered by this revelation and, without hesitation, transformed into Grigio Bone once again and once again Katsumi transformed into Rosso to take care of the kaiju. During the fight, Rosso held the upper hand at first with his R/B Sluggers, but then he went on the defensive and shielded Isami and Kaoru from Grigio's numerous Bone Breathters which left him weakened. After thinking back to his childhood and hearing inspiring words from Kaoru, Isami finally gained enough courage to regain the power to transform into Ultraman Blu once again and similar to earlier, Blu saved Rosso from Grigio with his Jumping Kick.

After both of them dodged another Bone Breathter, Rosso and Blu transformed into their Aqua and Wind forms respectfully. Blu then trapped Grigio inside a tornado and Rosso the same with a giant Splash Bomb. Blu then summoned his R/B Slugger and used the power Ultraman X 's R/B Crystal to attack Grigio with his Spark Attacker, which left Grigio stunned. The two brothers then destroyed Grigio Bone once and for all with their Flame-Aqua Hybrid Shoot.

When Saki Mitsurugi lends Makoto her Gyro, he initially tries to transform into Grigio Bone, but she swaps the crystal out for Grigio King. Makoto transforms into the monster to have his revenge against Rosso and Blu and beats them after they exhaust their greatest techniques. However, Saki commanded D.R.L.N to fire a tranquilizer ray from the Aizen Tech building at Grigio King, putting it to sleep. The authorities then restrained the immobile monster using cables. When the time was right, Saki reawakened the sleeping Grigio King, who promptly when on a destructive spree. The Minato Brothers come back to fight Grigio King again, but even with a new strategy, the monster was too tough. Once more, they tried using the Ultraman and Belial Crystals, but failed until Asahi came along and reminded them of their mother's words - that when the two of them are together, they can do anything. With that, they unlocked the power of Ultraman Ruebe, who fought Grigio King and destroyed it.

Saki encountered Katsumi and Isami while she was going back to Aizen Tech, and she told the boys to leave the planet along with their family. However, they refused, saying that they can find another solution. With no other choice, Saki transformed into Grigio Regina. Grigio Regina easily withstands all of the brothers' attacks, even Ultraman Ruebe's, as she marched on to Aizen Tech to detonate the planet. However, the Reugosite Crystal suddenly activated and forced her out of her transformation. As Reugosite freed itself from its prison, Saki could do nothing but watch the destroyer's arrival.

Saki once again assumed the form of Grigio Regina, trying to put her plan into action. She first tried to stall it until the Ray Energy gathered at the Aizen Tech building, which would allow her to destroy the planet along with Reugosite. However, all of her attacks were easily withstood by Reugosite. Grigio Regina and Reugosite then battled inside a barrier set up around Aizen Tech to prevent Reugosite from escaping. Saki absorbed the power of other R/B Crystals, gaining a power up, but Reugosite was still unaffected by Grigio Regina's attacks. Rosso and Blu lately arrived to help Grigio Regina by countering Reugosite's Genesis Requiem with their own beams and, reminded of her older brothers, Saki stepped in front and took the next beam Reugosite fired. Grigio Regina then disappeared, and Saki died.

Grigio Regina will reappear again in this movie, this time being controlled by Asahi Minato.

Bone

 * Burrowing: Grigio Bone can remain submerged underground for a very long period before returning to the surface.
 * Bone Breathter (ボーンブレスター Bōn Buresutā): Grigio Bone's primary attack where he spits flames of up to a million degrees out of his mouth. In Ultraman Fusion Fight!, he can also spit out several fireball-like blasts of this attack, before finishing with a stronger breath of fire.
 * Acceleration: Grigio Bone has the ability to run at fast speeds.
 * Bone Tail (ボーンテール Bōn Tēru): Grigio Bone's tail is strong enough to knock down two Ultras at once.
 * Bone Slap (ボーンスラップ Bōn Surappu): Grigio Bone slaps the opponent.

King

 * Grigio Barrel (グルジオバレル Gurujio Bareru): Grigio King has a large cannon mounted to his back.
 * Giga King Cannon (ギガキングキャノン Giga Kingu Kyanon): Its cannon can shoot a destructive yellow ray, which is strong enough to overcome the Triple Origium Ray. After firing the cannon, the Grigio Barrel has to cool down for about 2.5 seconds before it can be fired again.
 * Neo Bone Breathter (ネオボーンブレスター Neo Bōn Buresutā): An evolution of Grigio Bone’s Bone Breathter, being four times more powerful and countering the Flame-Aqua Hybrid Shoot.
 * Bone Shocking (ボーンシショッキング Bōn Shokkingu): Grigio King can conduct electricity through his touch to shock opponents. He can either send an electrical shock through the hand or empower his claws with electricity.
 * Tough Hide: Grigio King's exterior is much tougher than its predecessor's, not being affected by the R/B Slugger Blu and being able to catch and crush the Flame Sphere Shoot.
 * Claws: Grigio King has sharp, bladed claws for hands, which he can use in melee combat.

Regina

 * Erga-Trio Lancia (エルガトリオランチア Erugatorio Ranchia): Grigio Regina has three cannons on her body, one mounted on each shoulder and one on her chest.
 * Rapid Fire Cannon: The three cannons shoot a barrage of missiles.
 * Erga-Trio Cannon (エルガトリオキャノン Erugatorio Kyanon): Grigio Regina fires beams from all three cannons, which then merge into a singular, powerful beam strong enough to shatter the R/B Kourin's barrier and defeat Ultraman Ruebe instantly.
 * Regina Corsa (レギーナコルサ Regīna Korusa): A rushing tackle attack.
 * Regina Voltagio (レギーナボルテジオ Regīna Borutejio): Like Grigio King, Grigio Regina can also use electricity to attack, channeled through her horn and hands.
 * Regina Corno (レギーナコルノ Regīna Koruno): Grigio Regina's horn.
 * Corno Assault (コルノアサルト Koruno Asaruto): Grigio Regina attacks with its horn.
 * Spiked Tail: Grigio Regina's tail is split in two, and both points are covered in sharp spines. Considering Grigio Bone's earlier use of his tail as a weapon, Regina's is likely even more effective.
 * Tough Hide: Grigio Regina's exterior is even more sturdy than Grigio King's, being able to withstand the Ruebe Vortex Buster.
 * Flame Emission (Unused): An even further evolution of Grigio Bone's, it has enough power to match the Sun's thermonuclear reactions.