Blasters are a humanoid species that developed an aggressive space faring civilisation. The tried to conquer Earth in the early 21st century using giant mechanical monsters after having previosuly destroyed another world. They use the numeric system in their social hierarchy.
Source: [アストロガンガー] Astroganger (Astroganga) - Knack Animation. Information based on the fantastic site www.encirobot.com (Picture also from site).