One night, Madoka has a terrible nightmare – against the backdrop of a desolate landscape, she watches a magical girl battle a terrifying creature, and lose. The next day, the teen's dream becomes reality when the girl – Homura – arrives at Mitakihara Middle School as a transfer student, mysteriously warning Madoka to stay just the way she is. But when she and her best friend Miki are pulled into a twisted illusion world and meet a magical creature named Kyubey, the pair discovers that magical girls are real, and what's more, they can choose to become one. All they must do is sign a contract with Kyubey and agree to fight witches that spread despair to the human world, and in return they will be granted a single wish. However, as Homura's omen suggests, there's far more to becoming a magical girl than Madoka and Miki realize...
Japan, present day: Alien Invaders are everywhere, taking over peoples' bodies. Fighting them is Isuzu Ayane, an introverted young girl with the ability to control powerful dimensional Gates. Under the guidance of Kageyama Reiji, a mysterious businessman, she battles Invaders and recruits new Gate Keepers. Will she and her new comrades be able to save the earth?
Both of these animes involve young girls fighting against monsters that are not all they seem. While Gatekeepers also has male magic users, both of these animes seem to take the Magical Girl genre and shake it up. The character types are also very similar (whiny one, fighting one, emotionally challenged one... etc). Also, aliens.
Henrietta is a young girl who works for a "welfare group" that does the government's dirty work. Cybernetically-enhanced and specially-trained, she is one of a group of elite hit-girls, remorseless killers with no memories of their past. Jose, her partner, has taken care of her since she was brought into the organization following the murder of her family, and struggles between his affection for her, and his opposing duty to his employer. But, time is running out.. for with each bullet they fire, Henrietta and the other girls lose a little more of their humanity.
Both Mahou Shoujo Madoka Magica and Gunslinger Girl are stories that only feature adolescent girls as major characters. They also base their storylines on clichéd genres with stunning execution which provides a fresh breeze for the viewer. Little girls emotionally maimed by the horrible things they're forced to go through by their superiors is also a shared theme. If you liked one of them, don't forget to watch the other!
In the Middle Ages, a woman named Jeanne D'Arc claimed to hear God's voice. She led a lonely life and was burned at the stake, despite being the voice to lead France to victory in the Hundred Years War. In today's world, she is reincarnated as Maron Kusakabe, a girl whose mission is to prevent demons from stealing people's hearts. To do this, she must steal any artifact that they possess. Her best friend, Miyako, is a detective looking for the thief, without a clue that she's right under her nose. Will Maron be able to save the world from destruction, or will she be caught red-handed by her friend?
If you liked Mahou Shoujo Madoka Magica, I'd recommend Kamikaze Kaitiou Jeanne. Madoka Magica is well known as an anime that redefines the magical girl genre. It features dark aspects to this usually light-hearted type of show. Like-wise, Kamikaze Kaitou Jeanne touches base on this aspect of magical girl life. Both characters also have a supernatural side-kick who plays a sizeable role in the show's plotline. Even though Kamikaze Kaitou Jeanne is considerably older, and has plenty more episodes than Madoka, it also focuses on a school girl struggling to balance her two lives, and be the best magical girl possible.
if you liked Puella Magi Madoka magica or Kamisama dolls, you'll probably like the other, because both have a similiar dark overtone and take their respective genre to a new place.
there is also the similarity where the main (and in madoka's case titular) character takes a sideline role for the most part, making for some interesting story dynamics.