It is intentionally ambiguous, which has caused it to be handled differently across the franchise.
What's your avatar's gender?
Official database: "Off-limits"
Light novel: "Tetra-chan", looks female
Anime: "Tetra-chan", looks female
NAL mobile game: "Male", looks female
Why's it important to put baby in a corner?
Critterfluffy's answer hits most of the in-universe notes. In S02E12, Shiroe announces to Kinjo & Uru that he's
the Round Table doesn't want to keep paying 10,000,000 gold per whatever for its exclusive rights over Akihabara's guild hall, cathedral, and merchant facilities;
the new arrangement gives them just as much usage rights over what ...