|This article is about a/an ranger in J.A.K.Q. Dengekitai.|
- "Dia Jack!"
- ―Dia Jack's roll call[src]
Ryu Higashi (東 竜 Higashi Ryū) is Dia Jack (ダイヤジャック Daiya Jakku) of J.A.K.Q.. He is a former welterweight boxing champion of Japan.
Falsely accused of murder by greedy boxing promoters in Las Vegas when he refused to rig a championship fight, Ryu was intercepted by Joker when he was being extradited to Japan for prosecution. Offered the choice of working for ISSIS as part of JAKQ or serving his prison sentence, Ryu reluctantly accepted Joker's offer.
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Gaoranger vs. Super Sentai
Dia Jack is among the Sentai warriors seen in clips when Yusuke Amamiya (Red Falcon) lectured Gaku Washio (GaoYellow) about the past Sentai sword experts, showing him that the true sword wasn't the sharpest, but the one that feeds on courage.
Years later, Ryu fought alongside not only his own team, but every single Sentai ranger in existence, against the Empire of Zangyack when it attacked the Earth in the Great Legend War. After fighting against hundreds of Gormin and their Zgormin commanders. Akarenger noticed the fleet moving towards them, he gathered all the Rangers together and gave them the order to sacrifice their powers to wipe out the first invasion's armada. The Dia Jack powers are later utilized by Joe Gibken via the Ranger Keys.
Farewell Space Pirates
After the Zangyack's final defeat, Marvelous returned the Ranger Keys to their original owners. It is assumed Ryuu and his teammates have their powers once again.
Super Hero Taisen
Ryuu, alongside his team, among the majority of the Super Sentai heroes, was caught up in the "Super Hero Taisen" incident which eventually resulted in the Super Sentai teams and Kamen Riders joining forces to defeat both Dai-Zangyack and Dai-Shocker.
Zyuohger vs. Ninninger
Dia Jack appeared with his team among the first 38 Super Sentai whom collectively empowered Wild Tousai Shuriken King in its fight against the titanic Gillmarda, granting the Ninningers and Zyuohgers the power to perform the Zyuoh Ninnin Super Sentai Burst which destroyed Gillmarda with the combined power of all 40 Super Sentai.
Ryu is a rough and gruff individual who is at times very headstrong and tends to prefer working alone, though he continues to keep in touch with his former boxing partners. Ryu loves jazz music and fast cars.
Video game appearances
- Ryu Higashi/Dia Jack: A hot-blooded warrior empowered with electrical energy. He defeats many crimers with his natural speed and his Dia Sword.
Super Sentai Battle Base
Dia Jack is among the vast pantheon of Rangers which are available in the mobile game Super Sentai Battle Base.
Super Sentai Legend Wars
Dia Jack appears with his team among all Sentai in the mobile game Super Sentai Legend Wars.
As Dia Jack, Higashi's cybernetic enhancements enable him to manipulate electric energy which he primarily focuses through the powerful Dia Sword he wields, enhancing it's cutting power or firing bolts of electricity from it.
He is also equipped with an "Elek Cutter" [Electric Cutter] in his right second finger and the "Dia Laser" ins his left ring finger.
Dia Jack wears a blue cloth suit with white arms and a sash that possess several holsters within it with a bronze-colored medal around the right side with the letter "J", representing the Jack. His gloves are blue while his boots are white in color with black cuffs. A silver belt with more holsters surround his body with the buckle for J.A.K.Q. in the center; while with a small yellow cape around his back. His helmet possesses a blue diamond representing his card suite, surrounded in a field of white. Above the Diamond is the letter "J".
The Dia Jack Ranger Key (ダイヤジャックレンジャーキー Daiya Jakku Renjā Kī) is Ryuu Higashi's personal Ranger Key and what became of his powers after he along with the rest of the 34 Super Sentai sacrificed their powers to end the Great Legend War.
This key along with the majority of the Ranger Keys were collected by the Red Pirates and later used by the Gokaigers. The Dia Jack Ranger Key was mainly used by Joe Gibken (Gokai Blue), who used it to fight as Dia Jack.
- Alongside Marvelous, Ahim, and Don, as they became the original four Jackers while fighting Action Commander Nanonanoda.
- When the Gokaigers became JAKQ in their fight against Action Commander Zaggai.
- When the Gokaigers became JAKQ in order to use the Big Bomber cannon against Action Commander Shieldon in a vain attempt to penetrate his shield.
- As part of a bombardment of changes in the final battle with Emperor Ackdos Gill.
The J.A.K.Q. keys, along with all the Ranger Keys of the first 33 Super Sentai, were briefly taken by the Black Cross King and turned into Ranger puppets that were fought by the Gokaigers and the Goseigers. The J.A.K.Q. keys were defeated by Super Gosei Red.
After Zangyack were finally defeated, the Gokaigers gave the Ranger Keys back to their rightful owners. It is presumed that Ryuu received his key and became Dia Jack once more.
Behind the scenes
Dia Jack is featured as #54 in the 1986 archive compilation video Toei 100 Great Heroes Super Fight.
- Shares his first name with Ryu Tendo/Red Hawk from Choujin Sentai Jetman.
- He is the first Blue Ranger to have "ryu" in his name, and the only one to have the "dragon" kanji as a part of his name. This would be followed with Ryuuta Nanbara (Blue Three) from Choudenshi Bioman, Ryunosuke Ikenami (Shinken Blue) from Samurai Sentai Shinkenger, and Ryuji Iwasaki (Blue Buster) from Tokumei Sentai Go-Busters.
- His translated name, in Eastern format, is "East Dragon". This is a reference to the Azure Dragon (known as 青竜, Seiryu in Japan), the Dragon Guardian Spirit of the East.
- Ryu is the very first Sentai hero to use a sword in combat.
- In the Ishinomori Hero File Book, it revealed the concept designs of the JAKQ team. Dia Jack was originally intended to be the Red Ranger of the team, however, this was later changed as his color was swapped for Spade Ace's original blue color and Spade Ace became Red.  Despite this, a red hero from another franchise would later wear the Suit of Diamonds as a motif.
- Ryu is the only member of his team who did not join the Super Sentai Strongest Battle
- ↑ Ishinomori Hero File