Cassia () is the water planet, which consists of two large islands. The planet is mainly populated by otter people, and another magic academy, Ambergis Prep, established prior to Will-O-Wisp is located on Granule Island. Cassia is frozen cold when the player first arrives. The planet is home to the Aquarino, a water particle that neither freezes or evaporates as a side effect of being set on fire by the "Fire Otter". The planet is also home to the Holy Water Pyramid, home to the Water Millennium Gummy and the ancient race of water people.