As the largest prison in not only the Kunan region but the entire Toran Republic, Soniere Prison serves an important role as the maximum security prison, used to hold serious criminals such as murders or political prisoners; criminals convicted of lesser crimes are usually sent to the Banner Mines for forced labour. It was built in SY 347, built by the inmates of Gaya Prison; they were then transferred to Soniere Prison themselves, and Gaya was destroyed in favor of Soniere's use.
Though it is the most secure and heavily guarded prison in the country, Soniere has been destroyed twice in the past. It was first destroyed during a war between The Scarlet Moon Empire and Jowston, when Jowston advanced far into the Kunan region, forcing the Imperial Army to retreat into Soniere Prison, when the Jowston troops burned down the prison during the siege. The second siege occurred in a prison revolt, when the Master Thief Wilbourn convinced thousands of his followers and fellow prisoners to revolt against the guards. Wilbourne burned the prison down himself during the revolt, leaving 300 trapped prison guards and prisoners to their deaths. However, neither disaster kept the Scarlet Moon Empire from rebuilding it again.