On the planet Mercury, the advanced technology of cybernetic prostheses has led to the development of giant pilotable robots. However, prolonged use of these achievements in bioengineering takes a significant toll on a pilot's body. As the Merucians' mobile suits gain formidable power, fear rises among the people of Earth. On her daughter Ericht's fourth birthday, pilot Elnora Samaya tests the state-of-the-art Gundam Lfrith under the watchful eye of its creator, Cardo Nabo. Ericht visits Elnora at work despite orders not to, and chaos unfolds after she forms a strange bond with her mother's mecha.

Seiya and the rest of the Bronze and Gold Saints who have survived the Sanctuary battle have entered the world of the Dead. They are fighting to get to Hades and defeat him. (Source: ANN)

As the Holy Empire rises to power, the neighboring lands begin to gradually fall under its control. The Empire's conquest eventually reaches the small island of Erin, home to the Gael tribe. There, a priestess named Riannon is kidnapped to be offered as a living sacrifice to the demon king Arawn, a malevolent being rumored to have caused untold destruction in the past. Riannon's brother, First Warrior Arthur, rescues her, when Arawn suddenly materializes before them as a handsome grey-haired man. Hiding his true identity and remaining enigmatic, Arawn pledges his power and leadership to the tribe's cause and joins Arthur, Riannon, and their merry band of friends—including a talented swordsman, an agile hunter, and a group of ecstatic pixies—as they fight back against the Empire, while uncovering the dark secrets of the land along the way.

Kei Narutani and his childhood friend, Song Minghua, are Chinese refugees who are fleeing from the Zai, a mysterious organization that indiscriminately terrorizes their country and its people. Fortunately, during their escape to Japan, they are saved by a strange red aircraft. Kei's fascination with this aircraft leads him to meet his savior: a girl who is an Anima—the pilot of a unique type of airplane called a Daughter. The girl goes by Gripen, an adorable JAS-39F fighter aircraft. Kei develops a bond with Gripen and is then recruited by the Japan Self-Defense Force to help Gripen overcome her troubles with flying. Later joined by Eagle, a carefree F-15J-ANM, and Phantom, a proud RF-4EJ-ANM, the squadron takes up arms, determined to protect humanity. Together, the five individuals battle against the invasive Zai, forming the last line of defense against the threatening alien force.