Chikyuu Bouei Kigyou Dai-Guard

An alien species called the Heterodyne reappears thirteen years after vanishing. In response, three employees of 21st Century Security Corporation use Dai-Guard, a large robot once dismissed as a novelty. The robot is outdated and poorly maintained, but the team continues to rely on it. Despite the challenges, these office workers take on the responsibility of defending against the Heterodyne.