"The Green Baby" is a strange creature that Jolyne finds while escaping from the punishment cell. And the enemy Stand that swallowed it, "YA-YA MA". The seemingly obedient YA-YA MA and the boat with Jolyne and others on board go through the wetlands. However, what Jolyne and the others should really fear is not the guards' pursuit, but YA-YA MA's invisible stand attack...