Tenkuu Senki Shurato: Sousei e no Anto

Gai and Shurato have been erased from history, but the eight guardians are sent back to Earth to investigate another emerging threat. This new danger prompts them to return to a world that has forgotten Shurato, forcing him to try and regain his friends' trust in the process. Meanwhile, a new villain begins to implement a mysterious plan that has the potential to impact the eight guardians.