Humanity won the war against demons that had raged since time immemorial. The shadow of the demons finally departed, and peace returned to the human world. At least, people were beginning to believe so—.

Solm Bastide, the Prison City, a penal colony where criminals were confined. It was an isolated island on land, surrounded by imposing walls, And once inside, there was no escaping ever again.

Mika, the protagonist, a cleric incarcerated in the Prison City, Was, however, an honest and pure young man, seemingly innocent of any crime. Being an anomaly among the criminals, he was shunned by those around him, Though there were a few eccentric individuals who befriended him instead of abandoning him. Upon them, a great calamity would soon befall. When one of the criminals became a 'witch' possessed by a demon, The city enclosed by walls transformed into a stage for an inescapable tragedy. The threat of demons had not vanished; it was still very much present here. A place of execution meant to seal away demons along with the criminals, destroying them all—. That was the true nature of the Prison City, and the reason for peace in the human world. Beings that were once human went mad, broke, and attacked people. A ludicrous tragedy rained down in a shower of blood. Amidst the ever-spreading devastation, a voice whispered to Mika.

"Come, let us begin. Our journey, steeped in sin—"