Mitsuhiko Ishibori

Mitsuhiko Ishibori (石堀光彦, Ishibori Mitsuhiko) is the alias taken by Dark Zagi after he possessed a TLT scientist named Hajime Yamaoka back in year 1991, 18 years prior to the start of the series.

Pre-Nexus
Arriving in Colorado, where TLT, the Terrestrial Liberation Trust, was newly formed with help from the newly arrived Visitors, Zagi possess a TLT scientist named Hajime Yamaoka, killing his brain and turning it into an empty body for Zagi to use. He kills all of the TLT workers and scientist, with among them are Nagi's parents.

For five years while TLT was creating the division called, Night Raiders, Zagi hid as Mitsuhiko and manipulated the situation so that the power of Nexus could be strengthened to recreate his body. With the appearance of the second Dunamist, he began his plans sending ever more powerful Space Beasts and the Dark Giants Dark Faust, Dark Mephisto. By the time of the third Dunamist, Zagi was left with no Dark Giants of his own to command his monster legions so he backed them up with his own dark power. After displaying his power of the Dark Field G he would codenamed Unknown Hand, due to the fact the he never physically appeared as far as TLT knew. All of these creatures were intentionally sacrificed so that the power of Nexus could increased allowing him to regain his body. Following the fall of second Mephisto, he began the last phases of his plans, having his beast Mega Flash attack a city in broad daylight, creating the fear needed to increase his power, while weakening the power of the Visitors potential barrier which limited the appearance of Space Beasts. After the destruction of Izmael, Ren Senjyu, the third Deunamist seemingly died and Nagi Saijyo became the fourth. It was then that he revealed himself as Mitsuhiko for the first time Zagi told the truth of how he destroyed the lab that included both of Nagi's parents as a small child, traumatizing her, knowing she would turn to hate space beasts like Zagi planned. Leaving a shock and wounded team, Zagi departed to Level 0, where Lethe was housed, the power of the Visitors was now too weak to stop him. There defeated Komon, Captain Wakura, and Illustrator with Nagi shortly after. Zagi proceeded to tell the Night Raiders his entire plan. After Nagi turned into Nexus, Lethe, the storehouse for all the deleted memories of Beast attack survivors and based on the body of Zagi, synchronized with Nagi's emotions and memories and consumed all the energy in her body because of her hatred, allowing Zagi to absorb this energy in turn to restore his physical body with the human form vanished.

Powers and Abilities

 * Reflexes: Ishibori was fast enough to turn around and catch a bullet in his hand.
 * Protective Aura: When he performed that above maneuver his hand was covered in a dark blue energy that most likely protected him from harm. This same power appeared in shield form when he was being shot at.
 * Dark Field G Deployment: A subspace Field deeper into the minus range than anything previously encountered, he can use in human form.
 * Remote Viewing(Name Unknown): Ishibori most likely posses this ability or he could not have deployed his Dark Field G while he was with the Night Raiders or the times he was away from the action. He was also able to find and communicate with Mizorogi while he was another part of the base.
 * Dark Ultra Powers: Ishibori also displayed other powers related to his nature as a dark Ultra, mainly flying, barriers and energy shockwaves, abilities that surpasses every Deunamist, good or evil.
 * Flash Travel/Astral Projections: It is unknown if Zagi simply flash traveled or temporarily separated from his host body, given what his flash travel looked like when he was revived it was most likely he separated from Ishibori, or the wisp like form he took on was his 'Ultra Form' before his restored his body.
 * Mind Powers: Ishibori/ Zagi has the same mental abilities as the visitors, mainly erasing memories.
 * Night Raider Training: Ishibori is a trained Night Raider being proficient in the use of their arms and machines.
 * Hacking: Ishibori was a skilled hacker.
 * Halted Aging: Ishibori was actually old enough to be the parent of many of the night raiders but his body had not aged since Dark Zagi took it.

Transformation
Ishibori's transformation was done purely by will with the assistance of Lethe. When transforming his body radiated dark energy and the red lines on Zagi's body could be seen on his face while his eyes glowed red.

Trivia

 * Ishibori is unique among Ultra Hosts, not just because his Ultra was the villain of his series but because Zagi had possessed a human body killing the host mind, making him lesss of a human host and more of a human form.
 * This is also why he doesn't qualify for the Evil Ultra Host category because he is the Ultra in question but in a different spin on the Human Form trope.
 * When Ishibori used some of his powers his eyes glowed red in a similar manner to Shunichi Maki, however when he transformed his face also sported the markings of Zagi on his body.
 * It is unknown of he was still biologically alive but given TLT's entry physical examination he either used his powers to mask his nature or he used his powers can pass for a normal human. It should be noted that Ishibori was once injured by a Space Beast like a normal human being, requiring medical attention.
 * Ishibori's actor, Mitsutoshi Shundo was also a finalist to play Himeya. His actor was also aware from the start that his character would be the final villain of the series.