If you liked the Kurogane no Linebarrels anime, the Anime-Planet community thinks you'd like:
Naota Nanbada is a boring young boy who leads a boring life in a boring town. His older brother has left for America, and the closest he comes to any excitement is when his deadbeat dad has too much sake. But things change one day when a bizarre girl zooms up to him on a scooter and smacks him in the face with her guitar. What's more, once Naoto returns home he discovers that this strange woman has arrived ahead of him and moved in! Not only does she constantly engage in perverted activities with Naota's father and flirt with the young man himself, but she also claims to be an alien who is searching for the ‘Pirate King.' Now, Naota must learn to live with this new intruder, deal with an odd government agent who sports exceptionally large eyebrows and the mysterious Medical Mechanica, and come to terms with the fact that there are a variety of robots and weapons emerging out of his head - amongst other things. Perhaps boring wasn't so bad after all...
Kurogane no Linebarrels is essentially a trojan horse which appears to be Code Geass upon first inspection (atleast for the largest part).
However this horse is plentiful filled with "FLCL".
If you liked either of those, it's recommended to check out the other.
Half a year has passed since Sousuke Sagara took up the job of protecting Kaname Chidori and has started living like a normal teenager for the first time. A former child soldier, his view on the perils of everyday life is highly unconventional and in frequent need of violent adjustment; Kaname can only hope her endless assault will eventually get him used to normal life. But a shadow looms over their happy days as Sousuke's employer, the private army called Mithril, is attacked by a new unknown enemy. Suddenly outgunned, can Mithril afford to keep one of their best playing around?
In the year 3567, the human race has lost their once technologically-advanced world due to their negligence with the planet. Now, their lives are in jeopardy when machines known as Gardeners are sent from the moon to destroy all mankind. Tokito Aizawa is a hunter who makes a living by destroying Gardeners and selling them for parts, but his life otherwise is fairly normal – until now. One day, while in town, Tokito meets a mysterious girl named Tea who calls him by the name "Koichi"; and in the midst of confusion, a large group of Gardeners suddenly attack the city. Tea then grants an unseen type of machine called "Silver" to Tokito – a machine that might be mankind’s best hope of evading destruction...
In both cases for the male protagonists, soon after meeting a strange girl with missing memories, they begin piloting an outstanding mecha with unmatched power on the side of justice with her. While the leading male character from Gin-iro no Olynssis has a nickname of Koichi, in Kurogane no Linebarrels, the head male character’s name is also Kouichi. How more alike can you get when it comes to characters and introductory plot?
Hiro Hiyorimi is a boy who moved to the city to live with his sister; but as he was walking around town one day, he sacrificed himself to protect a girl from being hit by falling beams, and subsequently lost his life. Her name is Hime, and she is a princess who has the power to revive the dead with the flames of life. In return for reviving Hiro, he must work as a servant to protect her from any harm that comes her way. Yet even though Hiro now has a partially immortal life, his flames of life must be recharged daily or he will die yet again. Hime’s life is targeted by her siblings because the throne of the royalty is at stake, so Hiro must step up as a faithful servant to protect her life at all cost!
Both Series' Main character aims to do what is right.
As in Princess Resurrection, Kiro died then resurrected. He needlessly throws him self in the line of danger to protect everything he believes in(what he thinks is right).
As in Kurogame no Limebarrels, Kouichi is a young boy who is killed just like Hiro. Kouichi does what he wants throwing him self at what ever opposes his justice(which he thinks is right).
Side Thought: The Intro and ending musics are simular if you liked that too :)
In the year 2019, the Robotics Club of Central Tanegashima High School has only one goal in mind: to create a working replica of the giant anime robot Gunvarrel! But doing so isn’t easy as the club only has two members: Aki, who took over the project from her now-graduated sister; and Kai, a lazy gamer who’d rather be elsewhere. What’s worse, the school’s vice principal has decided their club is a waste of school funds and plans to shut them down! Now, the duo must convince her otherwise by winning a fighting robot tournament and gaining new, machine-savvy members, but when Kai accidentally stumbles upon an unbelievable conspiracy, the Robotics Club becomes the least of his concerns...
Giant robots piloted by kids and saving the world against all odds are common themes in these two anime. Linebarrels revolves around the main character and is more cartoonish, while R;N is more realistic and focuses equally (and well) on several characters, their relationships, and their backstories. Both are solid, entertaining examples of the mecha genre.