Shinenju

The in an object that is composed entirely of memories of Souls that have lost their way in the Dangai. These memories merge into one object and eventually return to the Human World.

Summary
The Dark Ones covet the Shinenju, as it is essential to their plot. Kisuke Urahara suggests to Ichigo Kurosaki to search for it before the Dark Ones are able to find it, and he requests for the help of Senna to find it. At some point, a group of Shinigami appear in the Human World and inform Ichigo that Ganryū, the leader of the Dark Ones, intends to use the Shinenju to collide the Human World and the Soul Society together, which would destroy both worlds. They also reveal that Senna is indeed the Shinenju. The Dark Ones interrupt shortly after and manage to kidnap Senna. They place Senna at the nexus of the Valley of Screams in order to draw the Blanks towards her and use their energy to cause the Human World and the Soul Society to collide. However, after the Dark Ones are defeated, Senna sacrifices herself to use the Blanks' energy to restore both the Soul Society and the Human World to their original positions.

Powers & Abilities
Blank Manipulation: Since the Shinenju is composed entirely of memories, it can be used to manipulate the Blanks to do various tasks, including drawing two worlds together or pushing them apart.