Aru flies through the Night Bazaar atop the horse, crossing multiple cities and eventually descending onto a stone island in the center of a white ocean. The horse explains this is the Ocean of Milk from which the gods once churned the nectar of immortality. A large tunnel opens into an abandoned office space covered with posters of different places, and a toxic stench permeates the air. It is the tourism headquarters of the Otherworld, though currently closed, with part of the tunnel boarded up. The horse leaves Aru there, telling her she can call on the mounts whenever she needs to.

Aru squeezes through the planks covering the boarded-up tunnel and reaches a cave, where a cauldron made of vapors contains blue, toxic-smelling liquid. The cauldron is quivering, as if about to burst at any minute. Something solid floats at the top, which Aru suspects is the third key. A statue of Shiva with his mouth open is bent over the cauldron.

Aru discovers Mini standing to the side, and the girls reconcile. They brainstorm on how to get the key, which is floating on what Mini explains is halahala poison. A sign near the cauldron warns that touching it will make it explode.