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.
I definitely recommend you either anime whether you've already seen one or considering to watch either Heroic Age or Isekai. They are both must watch animes which ill give 5 stars to. The main similarity is between the two main characters Age and Kenshi which both have the same feel of confidence and strength. Be warned Isekai has ecchi scenes however it is not excessive nor the emphasis of the show.
Arika Yumemiya is a poor yet energetic girl who has come to the city to become an Otome – a female warrior with the power to match an entire army. She quickly befriends her irritable fellow student Nina Wong and Princess Mashiro, the queen-to-be. With the help of her mysterious benefactor and abundant natural talent, she’s able to overcome the trials of everyday life in the competitive Garderobe Academy, but darker schemes are afoot. How will her new friendships fare, when secrets of the past and present are brought forth to spark a fight for the crown, and more?
While watching Isekai no Seikishi Monogatari i was often feeling as if i was watching Mai Otome. Both series have a very heavy sci fi/fantasy hybrid feel with main protagonists at a school for people training to use special magic/science type abilities. Both series also deal with societies which prevent certain individuals from fall in love due to the social constarints placed on them due to their positions. Although the genders are reversed they both are very similar in style and some story elements.
In the near future, Mars is covered with oceans. Within one of its cities, Gram River is just another kid trying to survive in the slums, until he finds himself right in the middle of a pirate attack! After nearly drowning, he finds himself aboard the pirates' ship, and is faced with a decision: be killed, or stay and fight alongside them. And thus, Gram joins the pirate crew in their quest to find the legendary treasure of Mars, but they aren't alone in their search. Now, while being hunted by the military, bounty hunters, rivals and even a few old friends, they search the seas of Mars for clues...
While Mars Daybreak isnt a harem it has the whole concept of the unknowing hero caught up in something bigger than his ordinary life. The lack of females is made up with a stronger focus on the main relationship which coupled with the under water combat makes this a great anime.
A troublesome girl named Aun has stolen her village's holy item and has run away to marry a rock star; and because this sort of thing has happened before, her adopted brother Photon, a slightly clueless boy with superhuman strength, has been sent after her. Along the way he stumbles upon a naked rebel named Keyne (who, consequently, is being chased by a pervert who can’t seem to keep his clothes on); and Photon, not knowing the culture of the girl, accidentally engages himself to be married to her. Now, through a series of unfortunate events, the fate of the galaxy is now in the hands of Photon and his band of idiots!
Both series were made by the same person, so it's no surprise that they share many similarities, but I'll stick to just one: the male leads in both series are an unstoppable force (not to mention simpletons). If you liked they guy in one series, you might enjoy watching the other series. Note that Photon, is much dumber than Kenshi and the series itself is even less serious than Isekai no Seikishi Monogatari.
In a far and distant future, men and women have become mortal enemies. Each living on seperate planets, an interstellar war is being fought between the two very different peoples. Hibiki, a mere 3rd class worker, finds himself in the middle of a huge space battle, facing the nemesis of mankind: Womankind!
This is simply a must see if you like space harems. lots of action and a great story. Both anime have that "dear in the headlights" kind of hero who is willing but not all that bright and a wide array of ladies to keep him occupied.