The GM is SupremeZero. The basis for this logic is that SupremeZero was the person who linked to the delay post, something that would normally be done by the GM, while being otherwise unassociated to this war.
On a completely different note,
The person responsible for the one who disappeared in the public was Caster.
When Caster moves, it leaves behind some sort of image or silhouette that acts as a form of scout before returning to its true self at the end of a turn.
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~Acting on Impulse~
Black Turtle still didn't MAJORA'S MASK