Centers around Kouichi Hayase, a fourteen-year-old boy living a mediocre life, until an accident turns him into the pilot of a gigantic robot called "Linebarrel" and leads him to encounter a mysterious girl.
Anywhere else, Hayase Kouichi is just a normal junior high school student. However, he’s become a part of the Linebarrel, made and lost friends, and discovered the thing that he wants to protect the most. And just as Kouichi reflects upon his life up to now, Linebarrel decides to finally show its true and ultimate form!