Mariemaia Khushrenada is the daughter of Treize Khushrenada, the Duke of OZ and Leia Barton, daughter of Dekim Barton and sister of the real Trowa Barton, conceived during the meeting between the two on Colony X-18999 (as detailed in the Episode Zero manga). Supposedly dying at an early age, Mariemaia later resurfaced as the figurehead of the Mariemaia Army, which largely consisted of soldiers who had been loyal to Treize. Thanks to her grandfather Dekim's grooming, she was fully prepared to ravage the Earth and take her place as the World Sovereign, believing this to be what her father, Treize, would have wanted. If Operation Meteor went as planned, the young girl would be ruler of Earth, as stated by her uncle, though, in fact, she would be a puppet ruler as seen by her grandfather. Mariemaia kidnapped Vice-Foreign Minister Relena Darlian so there would be no opposition to the Barton family's rule over the Earth. The occupation of Earth was quick with no resistance and victory seemed assured, that is until a number of insurgents, including the Gundam pilots fought back. Mariemaia felt that their efforts would soon be exhausted, until the populace stands up and Wing Zero destroys the shelter. Dekim urges her to take up her rightful place as ruler of Earth but Relena slaps sense into her, literally. She then saves Darlian's life when her grandfather tried to kill her. Lady Une soon has her rushed to medical attention. Soon afterwards she makes a full recovery and is adopted by and placed in Une's custody. Source: Gundam Wiki
Tada Banri is the main male protagonist of the series. Having had a nearly fatal accident shortly after high school graduation, he lost all memories from before then. He spent a year recovering and has now entered law school. Later on in the series, Banri begins to pity Kouko as she's always alone because everyone finds her beauty and wealth intimidating. Banri is shown to a "Ghost" of himself watching over him before losing his memory. In episode 7 of the anime, he and Kouko officially begin dating. It is revealed that Banri and Linda were childhood friends who attended the same class in highschool. It is later shown that Linda is the primary reason for Banri's decision to attend a university in Tokyo, with her being the one who suggested it. In episode 21 of the anime, Kouko breaks up with him. In episode 23 of the anime, he fully regains his memories prior to the accident and forgets everything that happened after. In episode 24 of the anime—with Koko's mirror as a catalyst—he remembers everything after the accident, meaning he gained his memories prior and after. The "ghost" of his past self disappears after finally hearing Linda's response.
Sa Kyung's older sister. She is the one that pulled Moon Bin underwater in the pool, and therefore responsible for his trip to the past. Ultimately raped and killed by Sali Tayi. Before her death, her body was in a comatose state, yet her spirit - both while she was living and dead - often visited Moon Bin.
Representing the demon Belphegor and the corresponding the sin of Sloth. Belphegor's appearance is a girl with long dark hair in a pony tail. She is hard working and sensible, to make her target fall all the harder. She is the middle child of the "Stakes of Purgatory." She is the fantasy version of one of the servants that used to bully Sayo Yasuda as a child. (Source: Wikipedia)
A classmate of Ryofuko and Chinkyuu's. Out of Herself, Rena, and Asumi, Nami seems to have the most common sense. She is a cheerful girl and is always kind towards her peers as well as the girl's teacher.
Navi has the appearance resembling what Echo will potentially look like in the future. That is, a tall, beautiful young woman with a large bosom and curvy figure, long pink hair, and horns on her head. She tends to wear a light-colored dress resembling a robe of some sort. She has marks resembling a Seikoku over much of her body. At once both wise and playful, Navi holds a great deal of knowledge and wisdom from the dragons of the past. She especially loves teasing Echo and Ash. However, she does care for both of them. Navi is no ordinary figure, but the incarnation of the Dragonweis, or the collective memories of all dragons since the beginning of time. It is she who will eventually decide who will win the battle between Echo and Mordred. (Source: Wikipedia, Seikoku no Dragnar Wikia)