Reirenkei

This article, Reirenkei, is property of Ten Tailed Fox

The reirenkei (霊連係, Soul Link) is a small square-shaped object, similar in size to the Hōgyoku, that was created by Kisuke Urahara to restore the lost Shinigami powers of Raian Getsueikirite and Ichigo Kurosaki.

Overview

Urahara holding the Reirenkei as its being released.

The initial reirenkei worked by having one person pour their reiatsu into it, and then releasing the object itself, causing a black reiatsu to target and envelop two set targets. The sudden jolt of reiatsu would restore the powers of both beings, but the stronger being would share its power with the weaker being. In the case of Raian and Ichigo, Ichigo had already begun to recover his powers (before his Fullbring training), and thus, he was the stronger being, sharing his powers with Raian. The downside to this was that the strain caused by two people using the same powers, via their linked souls, caused them to lose their powers again a month after regaining them.

The completed reirenkei.

Urahara later perfected the reirenkei by storing the cube within a large cylinder Kidō barrier, and having multiple people add their reiatsu to it. Once enough reiatsu was collected, the reirenkei would take the form of an energy sword. The sword would then pierce a Shinigami's Hakusui, causing their powers to permanently return.