Season 1

Hikaru Amatsuga is a middle school student who lives in Kita-Kagami City and one day, he hears cries for help and finds a mechanical lifeform in the shape of an arm named Alma. Before he knew it, Alma ended up connectin…

The Mecha-Ude user Aki Murasame transfers into Hikaru's class with the intention to secure Alma. She belongs to an organization named ARMS and she starts following Hikaru and Alma around 24/7 and Hikaru seems completely…

Hikaru and Alma are taken to ARMS HQ. There, Hikaru is told that he is not suited to be a Mecha-Ude user, and Alma falls under ARMS' protection. Meanwhile, multiple incidents where Mecha-Udes are forcibly ripped away fr…

Hikaru was dealing with the fact that he had to still go to school while learning to live with Alma, working as a member of ARMS, and being followed around by Aki.

Aki is finally able to track down the worm-type Mecha-Ude user who killed her family. But the person she finds is her younger twin sister Fubuki, who should've also died in the incident that killed Aki's family. Aki is …

An incident where most of the Mecha-Ude users in Kita-Kagami City lost their minds and go berserk occurs. Hikaru tries to find out more about what the cause of this is, which is the worm-type Mecha-Ude, Amaryllis. But h…

After a fierce battle with Amaryllis, Alma regains his memories. His expression seemed grim, so Hikaru asks him what's wrong, but then Alma runs away. In order to get clues of where Alma may have gone, Hikaru goes to AR…

100 years ago, the founder of the Kagami Group, Yakumo, ends up losing his life after unsealing Ordela, the originator of all the Mecha-Udes. And in the present, Ordela was once again dormant, but the Kagami Group was t…

In order to seal away Ordela, who had awakened once more, Hikaru and Alma work alongside Kagami, who had acquired an even more powerful human-made Mecha-Ude, and begin their attack! The truth comes to light about Kagami…

The true masterminds behind everything that happened appear before Hikaru and Alma and they end up being ARMS' leader Aljis, and his Mecha-Ude, Fist. And underneath Aljis's mask, they discover it's actually Yakumo, who …

Fist was plotting to take in Ordela's powers and take over this world to make it the new home for the Mecha-Udes. During the battle, Hikaru tries to protect Alma from Fist's attack and ends up close to dying. Kagami the…

Kagami successfully revives Hikaru, but he lets his guard down for a second and his body is taken over by Fist, who had obtained Ordela's powers. Hikaru rises again in order to get Kagami's body back. Alma vs Fist... Ho…