Kouichi Hayase, a fourteen-year-old with a lackluster life marked by bullying and daydreams of heroism, has a fateful encounter that changes everything. After a mysterious 'accident,' he gains a girl companion and a massive humanoid robot named 'LINEBARREL.' Empowered by this newfound strength, Kouichi is thrust into a whirlwind of battles, secrets, and camaraderie. As he navigates this thrilling journey, he discovers the true essence of life, forming new bonds, saying goodbye to the past, and shouldering great responsibilities that force him to confront the complexities of the world.