Mugen Senki Portriss

A world inhabited by robots in peace is disrupted by the emergence of a tyrant known as Dark Portriss, who seeks limitless power using a weapon capable of destroying space and time. The only hope to stop this threat lies with the Portriss Knights. A human boy named Yuuma finds himself transported into this world, joining three Portriss Knights in their efforts to confront Dark Portriss and prevent his destructive plans.