Defender's Emblem

A Defender’s Emblem opens one more squad slot for your battles. You hand it over in the Barracks, where the answer Unlock Squad Slot costs one emblem; once the Barracks has the most slots it can have, that answer no longer appears. Battles give emblems as rewards.

In the demo you get exactly one, for winning Break Through to the Port in First… Sludge?, along with 6 Zombie goo and 4 Town Gratitude. That battle is the demo’s only one, and the demo ends soon after it, so the emblem has nothing to be used for there.