Ryūjin Jakka (Zanpakutō spirit)

Zanpakuto Unknown Tales arc
When the rogue Zanpakuto spirit Muramasa appeared in an attempt to gain control of Ryujin Jakka through his own Zanaputo powers, Yamamoto acted first by producing a powerful barrier to protect his might partner to seal himself away from others physically and force himself into unconscious state so Muramasa could not prope his mind. Desperate to get Ryu Jakka, Muramasa staged a fake Zanpakuto rebellion by turning as many Zanpakuto spirits as he could on the Soul Society.

This eventually lead Muramasa to find Ichigo, whose proved powerful enough to destroy Yamamoto's barrier. By pretending Yamamoto was his prisoner, Muramsa was able to trick Ichigo into using his power to break the barrer, finally, allowing Muramasa to brainwash Ryujin Jakka and enslave it. Quickly, Muramasa used his new servant to demolish the incinerate the entire area.

Powers & Abilities
Immense Spiritual Power Ryujin Jakka is the oldest, most powerful fire type and has greater attack power than all other Zanpakutō in Soul Society. Its power is so great that even the strongest of Shinigami are afraid of it even at its base power.

Fire Manipulation: The release of this Zanpakutō comes with an extreme release of spiritual pressure affecting all in the area, and can be felt for miles upon miles across all of Seireitei. The aura of this spirit can disintegrate anything, changing it into nothing more than ash and engulfing the surrounding landscape in a blazing firestorm, the heat of which was intense enough to scorch the sky. Only powerful fighters such as Kyōraku and Ukitake can resist it, but even then only indirectly. Even in its Shikai power is enough to fight against the Shikai of two other captains simultaneously, both of whom had the reputation of being the strongest Captains in Soul Society while together. The flames created by Ryūjin Jakka can be controlled with great precision to attack only the targets it chooses and it also has power over the intensity of the flames.