65 million years ago, the knights of the Ryusoul Tribe were selected to participate in a war campaign against the dictating Druidon Tribe who sought to rule Earth. But the Druidon's war campaign was halted by the meteor that brought the age of the dinosaurs to an end, forcing them to flee into space. Meanwhile, the Kishiryu were placed in a deep sleep as a failsafe should the Druidon return. The chosen knights choose to live in peace while passing their mantle down across generations. In the present day, the Druidon return to reclaim Earth as the current generation of knights, the Ryusoulgers, battle them with the support of Ui Tatsui and her father Naohisa Tatsui.
When the brutal Boshin War breaks out in Japan, a group of inmates on death row unite to defend a fortress against the Imperial army.
