If you're looking for anime similar to Kurogane no Linebarrels, you might like these titles. All recommendations are made by Anime-Planet users like you!
After accidentally forming the legendary mecha “Aquarion,” Amata finds himself at a pilot-training academy where the flirty girls love to get a rise out of him, and the boys seem more interested in exploring mysterious holes and big bangs than harnessing their Elemental superpowers. It’s all awkward dates, hijinks, and threesomes until otherworldly beings start abducting powerful female students. As a mysterious megalomaniac plots interplanetary disaster, the fate of the galaxy depends on whether or not the hormone-fueled academy coeds can come together to fight evil.
These two mecha anime both involve fighting against people from another world using mechas which, imo, look identical. The male leads are extremely different, but both suddenly pilot a unique robot, all to protect a girl who seems to have a connection to this other world. Luckily, the guy is backed-up by his many teammates, even if they don't like/trust him at first.
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.
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.