D4

For the D4 weapon series itself, see D4.
 is the twenty-first episode of Ultraman Z. This episode is the first in the show's climactic D4 arc that continues to the series finale.
==Synopsis==
A new weapon has been developed from the recovered remains of Baraba that uses the abilities of the Extradimensional Being Yapool! Haruki and the others are against using this weapon’s terrible powers, but at that moment, the Brutal Space Monster Kelbim appears! The new weapon, "D4" is equipped to King Joe STORAGE Custom. Will Yoko be able to pull the trigger?!
==Plot==
On the uninhabited island of Nakanotorishima, a new superweapon, the D4, is about to undergo its first test. Created by GAF following analysis of Baraba's sword, left behind after he was destroyed by Z and Ace, the weapon is imbued with the same energy as the interdimensional portals utilized by Yapool and his legion of Terrible-Monsters.
After the weapon was activated, it left a massive crater in the island, erasing an area approximately 2 kilometres wide, according to Yuka's analysis of the test run. Director Kuriyama announces that GAF was impressed by the test, and that they have ordered a second D4, this time an advanced version referred to as the D4 Ray, to be loaded on to King Joe STORAGE Custom, augmenting its Pedanium Particle Cannon. Having seen footage of the test and the aftermath for himself, Haruki Natsukawa is left feeling extremely concerned about this decision.
Shortly afterwards, a team of mechanics and security arrive at the STORAGE HQ, led by Strategic Manager Mai Yuki, who install the D4 Ray into King Joe. Haruki, Yuka and the other members of STORAGE voice their concerns against the D4 Ray to Kuriyama, who explains GAF has determined the energy of the D4 to be 'under control', though Yuka responds by arguing that there isn't enough data available to determine what will happen if King Joe was required to fire the D4 Ray. Kuriyama then announces that to obtain this data, GAF intend to carry out a second test run, this time with King Joe's newly-installed D4 Ray. Haruki states that humans don't need to use such a weapon to defeat monsters, though Kuriyama counters by saying that humans have only been able to fight monsters because of the presence of Ultraman Z, a reason Yoko immediately takes issue at.
GAF considers Ultraman Z to be a 'wild card', and are concerned as to what could happen to humans in the fight against monsters if he were to leave the planet, though Haruki immediately replies with a point that Z would never abandon humanity, and that STORAGE can protect the Earth in his stead. Though Kuriyama agrees with the sentiments of everyone else, the decision to use the D4 Ray has already been made, and he can't change GAF's collective opinion on the matter. As he leaves the control room, complaining of a stress-induced stomach pain, he passes by GAFJ Captain Asano, who clearly shows symptoms of his possession by Celebro.
At the same time, the D4 Ray's installation was being finalized, having been lowered into place near King Joe's Pedanium Particle Cannon. As the GAFJ engineers celebrated their hard work, Haruki contacted Z, and asked him for his thoughts. Z, interestingly, chose a neutral approach, saying that it was good humans had found ways to fight monsters on their own. Haruki asked if humans should have access to such horrifying power, to which Z responded that the decision was up to humanity to make.
Suddenly, a golden meteorite crashed into the crater at Nakanotorishima. Yuka switched to a camera feed of the site just in time to see the meteorite transform, revealing Kelbim. Shota Hebikura, who had experience with Kelbim's species before, informed the rest of STORAGE that these monsters were known to attack and infest locations with a great deal of energy present. Yoko assumed the Kelbim was attracted to Nakanotorishima because of the D4 test, which Hebikura agreed with. Kelbim took to the air, and began flying at high speed towards Honshu; the space monster was estimated to reach Tokyo within 20 minutes.
Yuka realizes that Kelbim is likely headed straight for STORAGE HQ to seek out King Joe's D4 Ray, and Hebikura comes up with a plan; Yoko and Haruki are to set out with King Joe and Windom, with Yoko attempting to lure Kelbim away from the city while Haruki provides backup in the form of Windom, where once the monster is at a safe distance, they are to take it out. However, before they can go, Kuriyama arrives, flanked by GAFJ security agents. There, he informs them of an order given by GAF General Command - "The D4 Ray will be used in this operation." Furthermore, despite Yuka's objections, King Joe was to perform the task alone, and Windom was to remain on standby until further orders were given.
Further arguments break out between GAFJ and STORAGE staff as Yoko sets off to pilot King Joe into battle on her own, but Bako refuses to let her launch King Joe, refusing to believe in Mai's statement that JAERC simulations will allow King Joe to survive firing the D4 Ray. After some persuasion, Yoko is successful, and King Joe is launched at last, rising out of its hangar as meteorites rain down all around. To make matters worse, Kelbim finally arrives, and begins commanding the meteorites to transform, but King Joe enters the fight!
The activated meteorites begin transforming, revealing additional Kelbims. Haruki demands to be allowed to leave, but Kuriyama orders Hebikura to give the order to fire the D4 Ray. Instead, Hebikura agrees with Haruki's request, exclaiming that he's the one in charge of the operation and has the final word on whether the D4 Ray should be used or not. Outside the base, King Joe is close to being overwhelmed by the Kelbim, only for Haruki to arrive on the scene in Windom, levelling the playing field somewhat. One of the Kelbims is destroyed by a volley of missiles, only for the first one to emit the signal to activate yet more of the meteorites, and the two machines are outnumbered once again.
Yuka notices that the Kelbim sending out the signals, a type of vocal wave, appears to be amplifying a weaker signal sent to its antennae from above, and begins tracing the source of the weaker signal. Yoko and Haruki fight on, but both machines are overpowered, forcing Haruki to transform into Z, assuming his Alpha Edge form. Together, Z and King Joe manage to take down another one of the Kelbims, but yet more meteorites arrive. At the same time, Yuka successfully traces the weaker signal, determining it to come from outside Earth's atmosphere. Another Kelbim, far larger than the standard-size ones, is commanding her children to infest the Earth! Realising that this is out of reach for King Joe, Yoko informs Z of this new lead, who flies into space, coming face to face with the truly colossal Mother Kelbim! Immediately, Z transforms into his Delta Rise Claw form, and charges into battle.
Back on Earth, King Joe stares down the two active Kelbim, but has run out of Pedanium Missiles. Two more Kelbim join the fight; it seems as if there's no limit to the amount of them appearing. Both Mai and Kuriyama insist that Hebikura order Yoko to fire the D4 Ray, as casualties can be minimized if it were to be used now; the city has been evacuated, and no civilians are in the area, but Hebikura continues to refuse to give the order to use the weapon. Kuriyama refuses to listen, and continues to command the D4 Ray be used.
Meanwhile, Z manages to destroy the Mother Kelbim using Beliarok's Deathcium Slash, but her surviving children on Earth continue to fight on. If Z doesn't make it back to Earth in time, the stalling Hebikura and Yoko have done to prevent the D4 Ray from being used will be all in vain. However, after being struck by a volley of Ballistic Exclusive Spit shots from the active Kelbims, Yoko takes heed of Kuriyama's order, and fires the D4 Ray anyway! As reality itself seems to break around King Joe, a gigantic beam is fired from the Particle Launcher, completely obliterating the Kelbims! 
In orbit around the Earth, Z turns around to see a wave of energy appearing over Japan. In a state of horror, Haruki and Z realise together that the weapon was used after all. King Joe falls to the ground, too damaged to remain upright, as a red-coloured wave of destruction comprised of countless portals spreads outward from near STORAGE HQ, consuming everything in its path. Earth's dimension is starting to collapse. Arriving overhead, Z and Haruki resolve to prevent the collapse, and Z fires an empowered version of his Zestium Beam directly at the source of the collapse, sealing the portal, but leaving the devastation caused by the incident behind. A massive crater several miles long now lies where much of the surrounding area had once been. Though it seemed as if Yoko and King Joe had been caught in the explosion, as her cries of fear rang out through the speakers of the STORAGE HQ's control room, as the dust cleared, Yoko had survived, as Z had managed to shield King Joe from the blast in the nick of time, holding the incapacitated machine in his arms.
Remarking on what she witnessed during Z's efforts to stop the dimensional collapse, Mai immediately wonders what would happen if GAF had access to weapons of equal power to that of an Ultraman. Hebikura ironically echoes Kuriyama's statement that the GAF had deemed the D4 Ray 'under control'. Later that day, STORAGE is berated by members of GAF, including Kuriyama, for ignoring orders given by GAF General Command. For these infractions, STORAGE will be immediately disbanded. While Haruki and Yoko are deeply disturbed by this statement, Hebikura can only scoff at it.
===Haruki's Ultra-Navi===
*Haruki's Ultra-navi! 'Kay! Today we're showing this!
*Z Riser: Zero.
*Z: Here he is! Master Ultraman Zero! When we fought together with Geed, it was Ultra-exciting! He looks so cool in his cape!
*Haruki: I was so moved to be able to thank him in person, Mr. Z!
*Z: Me too! Thank you for everything, master!
==Ultraman Z and Ultraman Zero Voice Drama==
During his training to become a full-fledged Ultra warrior, Z is visited by his senior Ultraman Mebius. Z tells Mebius about how he ended up become Zero's disciple before Zero himself interrupts their conversation.
==Cast==
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===Guest Actors===
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===Voice Actors===
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*Narration: 
===Suit Actors===
*Ultraman Z: 
*Windom: 
*King Joe STORAGE Custom: 
*Kelbim: 
==Appearances==
===Ultras===
*Ultraman Z
**Alpha Edge
**Delta Rise Claw
===Kaiju===
*Windom
*King Joe STORAGE Custom
*Kelbim
**Mother Kelbim
==Trivia==
*The Nakanotori Island was made with the use of an actual prop instead of CGI.https://twitter.com/kg_magras30/status/1330575143047892992 The crater left from the D4's testing is also produced through this method.https://twitter.com/kg_magras30/status/1330582231975292928
==References==