Two years after the defeat of Galactor and the apparent death of Condor Joe, a cruise ship is attacked by Leader X, killing nearly everyone on board. One of the survivors, a young girl, is captured by X and rapidly aged into the bizarre, masculine-voiced villainess Gel Sadra. Though she has the appearance of an adult, Gel Sadra is not immune to throwing childish tantrums and behaving immaturely. 
In the midst of the revival of Galactor, the Science Ninja Team is called back into action, with a shady man known as Hawk Getz acting as the replacement for Joe. Getz is quickly revealed to be a Galactor agent in disguise (and had killed the actual Getz who was to join), and winds up killed by a mysterious feather shuriken. After hints spread in the first three episodes, Joe reappears in the fourth episode, having somehow survived his fatal injuries at the end of the first series, and rejoins the team. It is later revealed that he was rescued by an ex-Galactor scientist at the brink of his death, and was the subject of various cybernetic augmentations. 
Later in the series, a female scientist known as Dr.Pandora is introduced, who had lost her husband and daughter in the cruise ship disaster. Unbeknown to her, her daughter Sammie survived and is in fact Gel Sadra.

Due to dangers of decreasing resources and growing pollution, the International Scientific Organization is established to improve environmental conditions throughout the world. But an international criminal group, Gallactor, tries to achieve world domination by taking control of the ISO. Gallactor was created by a mysterious being from outer space known as Generalissimo X, who gives orders through its chief commander on Earth, the masked Berg katse. To fight Gallactor and its robot monsters, the ISO's Dr. Nambu enlists five brave youths into a combat squad called Gatchaman,the Science Commandos. Special scientific powers and dramatic birdlike costumes make the Gatchaman Squad a match for Gallactor, wherever on Earth it may strike. Ken(the Eagle) is the wise leader, assisted by sometimes-foolhardy Joe(the Condor), pretty Jun(the Swan), eager little Jinpei(the Swallow), and strong Ryu(the Horned Owl). Each has individual scientific weapons, but their main power lies in their aircraft, the Phoenix, which can transform itself into a fiery arrow capable of piercing the most massive threats. GATCHAMAN is a series of dynamic action and tension as ken, Joe, Jun, Jinpei, and Ryu hold themselves in constant readiness to meet each new threat by Gallactor to conquer the world. 
(Source: Official Site)

After Leader X is seemingly destroyed for good at the end of Gatchaman II, a fragment of him that survived grows and mutates into Z. With the head of the Egobossler family, Count Egobossler (and his two subordinates Mechandol and Kempler), Z is bent on destroying the Earth, and the Science Ninja Team, once more. 
In the wake of Anderson's death, Dr.Nambu has become the new head of the ISO, while the team is now confined to the Gallatown (aka "G-Town") underwater base. Engineer Kamo is introduced, and after the New GodPhoenix is destroyed early on, the team receives the new Gatchaspartan as their mecha. The Gatchaspartan has a special mode as well, called Hypershoot, that can only be utilized by Ken (with his new "Gatchafencer" sword). 
As the series progresses, it is learned that the radiation exposure from constant use of the Hypershoot is slowly killing Ken, and that continued use would mean death. Meanwhile, Z plans to destroy the earth with an antimatter asteroid, codenamed "Poison Apple".

An XFLAG and Tatsunoko Production collaboration, which they describe as "battle entertainment for girls". 

The anime features Akubi from Tatsunoko's Hakushon Daimaou TV anime and Pandora from XFLAG's Monster Strike smartphone game, which also has its own web anime adaptation.

Akubi appears in the original Hakushon Daimaou anime from 1969 as the daughter of the titular genie Hakushon. This October marks the 50th anniversary of the franchise. Pandora is a "girl of wishes" from the Monster Strike smartphone game, who has appeared in the anime adaptation as a mischief maker.
 
(Source: Anime News Network, edited)

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