Caterina

The title blackbeard is a working name to describe the military official who provides alternative criticism to Alex Riger's ideas.

Introduced in OVA2, his named is revealed by whitestache in OVA3 as Caterina.

His rank is probably Vice-Consul as this is what one of two men near him refers to him as.

Only he, the Consul-General and Riger have the power to order the Security Department to attack within Monopolis.