Hollow Absorption

Hollow Absorption is a technique used by the manifested spirit of Kōga Kuchiki's Zanpakutō, Muramasa.

Description
To make up for the lack of his Shinigami master, Muramasa is forced to rely on absorbing Hollows in order to remain materialized in the real world. When he absorbs a Hollow, a portion of Muramasa's strength proportionate to the Hollow's power is restored for a considerable amount of time. However, Muramasa notes his body is not accustomed to absorbing Hollows with large amounts of Reiryoku, such as a Vasto Lorde.

The Hollows kept within Muramasa's body are suppressed via his willpower, and when he fell into despair from being rejected by Kōga Kuchiki, the Hollows broke free, which are all reabsorbed shortly after via Muramasa's unstable energy, leading him to a horrific Hollowfication.