Originally a labor immigrant from another star system after Miltia became a republic, he worked as a mine laborer along with his son, Tethlla.
However, the degradation of working conditions that resulted from the transfer of mining rights from the Miltian government to the U-TIC Organization led to a increase in anti-U-TIC Organization sentiment. As a result, he became a central figure to the quasi-resistance organization against the U-TIC Organization.
Though that resistance was later defeated by the U-TIC Organization, Aizen, in his love for the mine, remains there today with his granddaughter, Mai Magus, hoping for the mine's revival.
People like Aizen, as immigrant workers not aware of Miltia's transformation from theocracy to republic, busied themselves with complaints about their own circumstances, viewing the world with a somewhat narrow-minded perspective.
Xenosaga Episode III: Also sprach Zarathustra Edit
Aizen and Mai appear at the mine in the subconscious of Shion Uzuki.
- He is likely inspired by Isaac Balthasar from Xenogears.
- It is unknown if Aizen survived the Miltian Conflict so his status is unknown. Given that he and Mai are so connected to the Dabrye Mine and would likely not want to leave it, there is no reason to believe they survived.