In the distant future, mankind has mastered space and spread empires across the galaxy. While many choose to colonize distant planets, others choose to remain amidst the stars, ultimately giving rise to a new brand of humanity known as the Abh. Both genetically and culturally different from their Earth-dwelling peers, the Abh soon find themselves engaged in a bloody war that rages across hundreds of planets and set out to restore peace by means of conquest. Enter Jinto, a nobleman and ambassador of the recently acquired Hyde system whose duty is to represent his peoples' interests and rule on the Abh's behalf. In order to be officially coronated to this position, a cold-but-beautiful Abh princess named Lafiel arrives at Hyde to escort him back to the empire's capital. When they are suddenly attacked by an anti-Abh liberation front, however, the festivities are cut short, and the two must flee for their lives against all odds.
Kazuki Yotsuga is able to see things that others can't; in his visions, giant robots battle it out in the streets, causing massive damage in their wake. Though his visions have made him an outcast from the rest of his peers, they have attracted the attention of Ken Sanada – a physicist who believes Kazuki’s visions are a gateway into a parallel world! He places Kazuki into one of his inventions and accidentally sends him to the parallel world in his visions, where he finds himself in the middle of a war for control of the world! Kazuki must now become a pilot of one of the robots in order to join the fight for peace, all the while trying to find his way back to his own world…
The Joker Cluster is a group of 4 solar systems, inhabited by thousands of countries and millions of people. Amongst the kingdoms, men called Headd Liners pilot mecha known as Mortar Headd, which are also manned by fatima, android women who act as the bridge between the machine and its pilot. Ladios Sopp is a young man on his way to an android auction, where he hopes to retrieve a fatima from his past, Lachesis. But retrieving her will be no easy task, and along the way, he will meet new friends and make new enemies before reaching his goal.
Gonzo does it again with this action-packed mecha comedy. She's an ordinary high school girl. He's a counterterror agent assigned to protect her from those who would steal the information locked in her mind. OK, so she's not so normal after all. Armored Slave battles and lovers' spats abound as Sousuke and his comrades try to track down the mysterious Gauln before it's too late.
While the similarities might seem vague at first, I found the characters from both series to be somewhat similar. Both sets protagonists come from very different backgrounds and act as a foil against each other, while the series as a whole focuses on their interaction and bonds they make with each other. Full Metal Panic! is much more light-hearted and comedic but the main characters are very likeable.
Ever heard of a flying train? Tetsuro, living on a dismal earth, wants to ride it to Andromeda so he can get a mechanical body that will enable him to live forever. With the help of the mysterious woman, Maetel, Tetsuro braves many adventures on his way to Andromeda, heading towards a showdown with Count Mecha, an evil tyrant that brutally murdered his mother for sport. Will Tetsuro have the inner strength to face this monster on his own turf?
Far, far away in a distant time, there is a tribe of people called the Golden Tribe who have the ability to create stars and foretell the future. They gave out a warning to those who have yet to mature: 'Move.'. Three tribes answered their call: the Silver Tribe, the Bronze Tribe, and the Heroic Tribe. Soon after, the Golden Tribe encountered a crashed ship in which only a baby human known as Age survived; they named the child's race the Iron Tribe and assigned one of the few living members of the Heroic Tribe to protect him and his race. Now, in a distant part of the galaxy, humanity is threatened with extinction at the hands of the other tribes. With only a prophecy to go on, they set out to the deepest depths of space to find their savior named Age -- humanity's last hope.
Both are epic space operas. While in Heroic Age it tends to focus a lot more on the space battles and as opposed to Crest of the Stars where the space battles while still important are not a major part of the story. Each series also has a romance of sorts that develops between the male and female lead though in Crest of the Stars it isn't shown as much as. One of the definite good points in each series is the music with each series displaying a musical score that fits each series prefectly. I'm sure that if you liked one of them then you'll probably like the other one as well.