Expel (エクスペル, Ekusuperu?) is the fourth planet from the Arcura System, located in the Theta Sector, and is the main focus of the first half of Star Ocean: The Second Story.

Dictionary Entry

A planet located in the Arkula System of Sector Theta that has an atmospheric composition and surface gravity approximately identical to those of Earth.
This naturally beautiful world is currently enjoying a period of stability, but at one point in its past the high density of Energy Stones distributed throughout its atmosphere polluted the entire planet. This mysterious pollution, which began in 366 SD, continued for several years, and affected the psyches of many of the planet's wild animals, causing them to ferociously attack the native Expellians. However, in 371 SD, Dr. Neuyman succeeded in developing his Neuyman Purifier, a device that was able to remove this pollution. This cleaner worked wonderfully, removing most of the pollution by the very next year, and thereby eliminating almost all of the negative influence of the Energy Stones. Recognizing the value of this technology, Expel was invited to join the Pangalactic Federation at the end of the same year.
Because Expel is one of the few planets that generate Energy Stones - a necessity in the creation of Quadratic Keys - the planet is an extremely influential voice within the Pangalactic Federation. The current Prime Minister of Expel is Ms. Eleanor T. Kross (age 36).


Spoilers, plot and/or ending details follow. (skip)

Star Ocean: The Second Story/Second Evolution

In S.D. 366, the Quadratic Sphere fell on Expel, causing its orbit to drastically change, and several cataclysms in the planet itself, such as the destruction of the entire kingdom of Ell, earthquakes, and the increase of the monster population in the planet. The resident Expellians called the object the "Sorcery Globe", due to its nefarious influence to the planet. This meteor caused mutations on Expellian animals and citizens, as well as great, re-occurring earthquakes. Although it was too big to be noticed, the Quadratic Sphere also drastically changed Expel's orbit around Arcura.

Three months after the land of the "Sorcery Globe", Expel collided with the Class 9 energy mass surrounding Energy Nede, which completely destroyed the planet. Fortunately, after the defeat of the Ten Wise Men in Energy Nede, the Nedians used their final powers to "revive" Expel by using the time displacement technology to bring it forward in time from just before its destruction. After Energy Nede was erased from existence, Expel returned to be from its ashes.

Spoilers end here.