Just Because!

The series is set in 2107, a year in which little conflicts erupt all around the world. A group of four individuals—Aoi Hidaka, Kurara Tachibana, Sakuya Kamon, and Johnny Bernet—are selected to operate the Dancouga Nova, a mysteriously enormous robot that "protects the weak" and puts an end to these small-scale warfare. The Nova Eagle, Nova Rhino, Nova Liger, and Nova Elephant combine to produce the Super Robot Dancouga Nova, which is a combining robot kind of Super Robot with four independent parts, each with its own pilot. A covert organization that runs the Dancouga Nova and dispatches its pilots on designated missions from its headquarters of operations, the Dragon's Hive, is the source of the pilots.