Around the years 1860-1888 the Unleashing took place.
The Unleashing is the name for the disaster that occurred in the Kuze Shrine. It is both the spilling out of the Rift from the gates of the underworld, and the reflection of the pain contained by the Tattooed Priestesses back to those who offered the pain in the first place. The Rift, contained by sacrificing maidens by impalement in the Chamber of Thorns, was unleashed by Reika Kuze. Reika allowed her tattoos to enter her eyes, causing the sealed doors of hell to open, and the Unleashing to occur. Because of this event, the Rift spread into the Kuze Shrine and into the real world, cursing those who it engulfed.
After its initial release, unlike the Calamity and the Repentance, the effects of the Unleashing spread very slowly. Even after it occurred, Yashuu Kuze still considered it safe to send Hisame, Minamo and Shigure to impale Amane at the bottom of the Abyss, relatively close to the source of the Rift. This bought them the time to summon Shrine Carpenters, who could seal the Kuze Shrine and prevent the Rift from spreading any further.