A recent discovery I've made is in one of Rico's logs: "MUUT DITTS POUMN" When translated, they mean Motavia, Dezolias, and Palma, 3 of the 4 planets in the Argo System, where most other Phantasy Star games take place. Those 3 planets make up the seal on The Profound Darkness, the supposed purest incarnation of evil. Every 1000 years, the seal weakens, and TPD can release another Dark Force (Dark Falz) into reality. It does this to try and break the seal. The 3 parts of the seal are based on the planet's climates, one being a tundra, blue, one being a desert, red, one being a grassland, green. This also is made reference to by the item, Three Seals.