Saki Mitsurugi

"An old friend said, "To know the way to heaven, you must know the way to hell.". We have found a monster that will reach Earth for the first time in 1300 years. That monster's estimated time of arrival is two months later. Meanwhile, we will carry out an annihilation operation that will split Earth into fragments as a result. If you have any means of escape, please run away. Those who cannot escape ... I'm sorry."

- Saki Mitsurugi in Aizen Tech's announcement news.

Saki Mitsurugi (美剣) was the alias taken by a mysterious girl who is the secondary antagonist character and anti-villainess of Ultraman R/B, replacing Makoto Aizen/Cereza from episode 16 until 24, she is an addition to the cast later on in the series.

Originally credited as the Mysterious Woman (謎の女性) in episodes 11 to 13, she reveals her name during her first meeting with Asahi Minato. In episode 24, it is revealed that her real name is Grigio (グリージョ).

Personality
Not much is known abut her personality in the past, but it is shown that she cares for her older brothers very much. Because of the loss of her brothers, she became a cold-hearted person, hardly caring about individual lives. She is also shown to bear resentment the Minato brothers due to being Rosso and Blu's human hosts and calling them "fake Ultramen", due to them being "amateurs" compared to her older brothers yet she envies them for being able to draw out the Gyros' true power (transforming into Rosso and Blu) while she is unable to. She also cares for their sister Asahi, and considers Asahi as her friend, due to being Makoto Crystal. She is also very determined to somehow restore her brothers and to take revenge against Reugosite, no matter the cost, saying that the entire population of Earth dying in her plan to destroy Reugosite would justify for her brothers' sacrifice 1300 years ago. During her dying moments, she feels remorse for what she had done and gives her Gyro to Asahi, and says that she is happy to have met the Minatos.

Pre-Ultraman R/B
A long time ago, Grigio and her brothers climbed up the Warrior's Peak of Planet O-50, where they received the Gyros and R/B Crystals.

Grigio as Grigio Bone, alongside her brothers Rosso and Blu were the three warriors sent from Planet O-50 to defend Earth from the threat of Reugosite. However, the siblings lost the battle and crashed down towards Earth as a meteor, in a place that became known as Ayaka City, spreading Ray Energy throughout 1300 points of the Earth as a result of the impact. Grigio grieved over the loss of her brothers, who had become scattered as the R/B Crystals. From then on, she made it her mission to destroy Reugosite once and for all, no matter the cost. Following these events, Grigio traveled around the Earth for centuries and had met several notable figures and while doing so, planted world trees to stop the dispersal and reverse the flow of the Ray Energy. Many years later, she confronts Mio Minato, who was fleeing Aizen Tech, to obtain the two Gyros. However, before she could accomplish anything, a device nearby activated and pulled Mio into another dimension. Saki tried to save her, but she was too late. All that was left was candy.

Ultraman R/B
"Brothers?"

- Grigio's first word in episode 12

Grigio (Alias, Saki Mitsurugi) first shows up after Ultraman Orb Dark defeats Horoboros, and she takes its R/B Crystal. She then appears when Orb Dark and Ultramen Rosso and Blu start to fight, and she summons Horoboros, which somehow evolves into its Bipedal form. After Horoboros defeated the Ultras, Saki called the Kaiju back in its R/B Crystal before summoning again later on to fight Rosso and Blu, who was able to defeat it with the Triple Origium Ray. Afterwards, Saki posed as a nurse and entered Aizen Tech and meeting an injured Makoto Aizen for the first time. Saki also shown her interest towards Asahi, leaving the R/B Crystals of Belial and Ultraman behind after meeting her personally and having a brief conversation with her before lending Makoto her Gyro, stating that she despised weak Ultramen, and allowed him to transform into Grigio King. Makoto successfully took his revenge against Rosso and Blu. Saki then declared herself as the new master of D.R.L.N. while overseeing the battle.

Seeing that the brothers could not use the two new Crystals, she had D.R.L.N. activate the Monster Restraint System, but later rescinded it. Following Grigio King's defeat by Ultraman Ruebe, Saki separated Cereza from Makoto's body and trapped him within the building premises and took over Aizen Tech as its new president, replacing Makoto, who had returned back to normal. However, this was all part of a much bigger plan, which was to turn the planet into a bomb using Ray Energy and use it to destroy Reugosite, who she predicted to be coming in about two months. Saki continued to interact with Asahi, trying to convince her that she was not really part of the Minato family, though her attempts fail.

After taking over Aizen Tech and announcing her plan to destroy Earth, the governemnt and public decide to take drasric measures against her, which resulted in the hacking of D.R.L.N., who unleashed King Joe. During King Joe's attack, she worked with the Minato brothers for once to protect Asahi and she explained her backstory to her. After the battle, Saki used the Monster Restraint System on Ruebe, knocking him out. She then took the opportunity to steal the other two R/B Gyros to further power up her own Gyro and powers. During Gomora's rampage, she attacked the Minato Brothers who wanted to take back their Gyros, but they were protected by the Gyros themselves.

She then transformed into Grand King Megalos to finish off the monster and defeat both Rosso and Blu for being 'fake Ultramen' but was defeated after a tough battle. Later on, she told the Minato Siblings about their mother's disappearance before becoming Horoboros in an attempt to defeat Rosso and Blu but loses the battle once again. Afterwards, Saki rushes to the place where Mio disappeared as the siblings followed her. With all three Gyros gathered, a strange device activated, opening a portal to another dimension. Out of it came Mio Minato and Kamisori Demaaga and seeing that the brothers could not transform, Saki fought as Horoboros, but was easily defeated due to not having recovered from her previous fight.

Although severely weakened, she fought again when Kamisori Demaaga reappeared, but she was once again easily defeated. After Rosso and Blu defeat the monster, she finds her Gyro stolen. Saki finds out where her Gyro was - with Mio Minato - and took it back along with Reugosite's crystal just befire it could be thrown into the other dimension Mio came back from. She told them that she was going to destroy Reugosite no matter what and elaborated on her plan to use the Ray Energy to materialize Reugosite and destroy it along with herself and the Earth.

Saki then left, to say goodbye to Asahi. Encountering Katsumi and Isami again while she was going back to Aizen Tech, 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.

"To have met with you guys... I am happy..."

- Grigio's last words to Asahi

Saki transformed into Grigio Regina again soon afterwards in an attempt to stall him for long enough for the Ray Energy to gather at the Aizen Tech premises, so that she could finally destroy Reugosite and even had a barrier placed around the battlefield. However, all of her attacks proved ineffective even after absorbing more energy from other R/B Crystals. Later, the Minato brothers transformed into their Ultra forms to aid her, but were similarly outclassed by their formidable foe. Reminded of Rosso and Blu's sacrifice in the past, Saki has a change of heart and stands in front of the brothers to protect them from Reugosite's laser. Mortally wounded, she tells Asahi of her real name and passes on her Gyro before fading away in particles of light.

Powers and Weapons

 * Longevity : Saki has lived a very long life, having met Tokugawa Ieyasu during the late sixteenth century, as well as figures such as Oscar Wilde , William Shakespeare , and Niccolò Machiavelli.
 * R/B Gyro -Saki Mitsurugi Specification- : A repainted version of the original Gyro, it sports orange and black accents. She passed the device to Asahi during her dying moments.
 * Kaiju Summoning/Transformation : In the same vein as Makoto Aizen, scanning R/B Crystals allow her to summon or transform into the corresponding Kaiju.
 * Empowerment : A unique feature of her Gyro, Saki can evolve monsters summoned from R/B Crystals into their stronger forms, or at the very least grant them new powers.
 * R/B Crystal Creation : From a monster's remains, Saki can extract their essence and condense it into a R/B Crystal.
 * R/B Crystals : Although she is yet to have her own set, Saki can still use the R/B Crystals on her own Gyro.
 * Ray Energy Absorption : Saki can absorb the energies of R/B Crystals to gain an increase in power through the Ray Energy. She uses this as a suicide attack while letting Reugosite fire his beam, which will cause Earth to be obliterated if hit.
 * Kaiju Return : Saki reverts a summoned monster back to its R/B Crystal, which flies back to her.
 * Teleportation : Saki is capable of disappearing within the blink of an eye, doing so to escape before Katsumi witnesses her presence.
 * Energy Pulse : Saki releases a pulse of energy from her hand, which was used to expel Cereza from Makoto Aizen's body.
 * Barrier : Saki puts up an energy barrier to defend herself and others.
 * Healing Wave : Saki is able to heal people, seemingly at the expense of her own energy.
 * Repulsion Wave : Saki can release an orange wave and keep others at bay.
 * Energy Bolts : Saki can rapidly fire orange energy bolts from her hands.
 * Ray Energy Bomb : Saki can destroy the whole planet if she gives up her life force to become the detonator of the concentrated Ray Energy around the impact site of the Ayaka Star.

Kaiju

 * Horoboros: Retrieved after the Kaiju's first defeat
 * Grigio King: Unknown
 * Neronga: Unknown
 * King Joe: Retrieved after the Kaiju's defeat
 * Grand King Megalos: Unknown
 * Grigio Regina: Unknown
 * Red King: Possibly taken from Makoto Aizen.
 * Gargorgon: Possibly taken from Makoto Aizen.
 * Gue-Basser: Possibly taken from Makoto Aizen.

Ultra

 * Ultraman (Given to Asahi Minato)
 * Ultraman Belial (Given to Asahi Minato)

Other

 * Blank Crystal

Quotes
Whenever Saki expresses her thoughts towards the Ultramen or when talking to others, she will occasionally quote a statement said by one of the historical figures she met in the past. She usually starts with "An old friend once said.....".
 * "Most people are other people, naturally", that goes for those Ultraman, too. "Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation." (Oscar Wilde)
 * "All the world's a stage, and all the men and women merely players." (William Shakespeare)
 * "To know the way to heaven, you must know the way to Hell." (Niccolò Machiavelli)
 * "There's only one thing worse than injustice, and that's justice without her sword in her hand." (Oscar Wilde)
 * "There is something terribly morbid in the modern sympathy with pain." (William Shakespeare)
 * "The greatest mistake of the world, is differentiating between good people and bad people." (Oscar Wilde)
 * "The final target of all living things is, death." (TBA)

Trivia

 * In her intro card during the opening sequence, there are three gray blobs which seem to vaguely resemble the three Grigio variants.
 * The color of her fingernail paint represents the siblings of hers:
 * Red: Rosso
 * Blue: Blu
 * Gray: Herself
 * For reasons unknown, she disguises herself when meeting different people, such as a nurse (towards Makoto) and a high school girl (towards Asahi).
 * Her given name is shared with an alien girl from Ultraman Tiga, who also wears black clothes and has been on Earth since the ancient times.
 * It is unknown how Grigio could be Rosso and Blu's sister, since she is not an Ultra being like them.
 * Her death is similar to Riko Saida from Ultraman Nexus, in fact, they both faded away into particles of light after protecting the main characters.