In 2019, Kaito Yashio and Akiho Senomiya are the sole members of the Robotics Club at Central Tanegashima High School in Kyushu, Japan. Kaito is a laid back student and a skilled gamer who is just trying to help Akiho, his childhood friend.
She is an energetic positive-thinking girl who yearns to complete the ongoing project of the club: building a functional replica of Gunvarrel, the main robot of a once popular TV series. As they gather new members and try to assemble the robot, Kaito starts stumbling upon secret reports that might reveal a conspiracy of large proportions. Unaware of what he is actually dealing with, Kaito little by little starts discovering clues laid by the mysterious Ko Kimijima.