
Rykros as it appears in Phantasy Star Universe
Rykros is the fourth planet of the Algo star system. The planet remains hidden for most of its 1000-year, highly elliptical orbit.
Phantasy Star IV[]
A priest in Gumbious Temple on planet Dezolis tells Chaz and company to find Rykros before the Profound Darkness does; and that to do so, the Aero-Prism will show the way. Rune, as the Lutz of the current era, recalls that the artifact has been stored in the Soldier's Temple on Motavia east of Krup. When the party returns to Motavia, Demi prepares a hydrofoil for them to cruise over water.
Upon retrieving the Aero-Prism, the refracted light beams toward the sky, exposing the scholar Seth as a manifestation of Dark Force, whom the party battles and dispatches. Meanwhile, the android Wren picked up on the trajectory of the light and would enter the coordinates into the Landale.
Just as the party is traveling toward Algo's outer limits, the Aero-Prism shines once more, its light revealing the long-hidden planet.
Docking with Silence Temple, the four heroes are welcomed by the mysterious Le Roof, who then proceeds to test them before he anoints them as Protectors of Algo. They ascend the planet's two towers and confront their guardians in combat to procure the five Rings of the Stars. Le Roof then tells the four of Algo's true purpose and the role they are to play. Chaz objects, but Rune offers a different motivation and another trial back on Dezolis.
Chaz can optionally return to Rykros to acquire Megid from the Anger Tower in the southwest.
Phantasy Star Portable 2[]

Rykros Scenery in Phantasy Star Portable 2.
"The site of the final battle of the Seed Crisis three years ago. Called the "dark planet," it was the source of the Seed plague.
Originally constructed by the Ancients as a space fortress and the ultimate weapon against the Seed, it was corrupted by Dark Falz and had become a nest that produced never-ending waves o Seed.
The four confinement systems activated during the Unification Point three years ago sealed away Rykros along with Dark Falz"
In-game Description
Rykros had returned in Phantasy Star Portable 2, sealed away by the Gurhal community, but returned through sub-space for the reason that the codex laid in the ruins that Shizuru Shu, while possessed by Kumhan, was hunting for.