In Episode III, the planet is revealed to have been obliterated by the Gnosis over 15 years beforehand and that Kevin Winnicot was a survivor from Michtam. It is also the birthplace of Ormus and first planet settled by the people of the Immigrant Fleet after they left Lost Jerusalem. It is where "God's relics" were kept, primarily the Zarathustra device. Michtam also serves as the location for the last quarter of the game where the stories most of the series' cast (over 15 different characters) are resolved.
Michtam is an allusion to Miktam04β, a planet mentioned in the Xenogears Perfect Works encyclopedia. In that continuum, Miktam04β is said to have been destroyed by Deus when it absorbed too much energy from the Zohar, and the Eldridge was sent to rescue surivivors. This event was pivotal in setting the events of the next 10,000 years into motion.