Servicing the trains for a living, Ikoma uses his spare time to build a weapon that could defeat the Kabane.
While the last of humanity has retreated into fortress-like stations connected by armored trains, some remain as hopeful as Ikoma.
The series was an interesting from a design perspective as it reunited some Attack on Titancolleagues with director Tetsuro Araki and writer Ichiro Okouchi.