Modified Souls, popularly known as Mod-Souls, are artificial souls created to enhance normal human physiology. This is to make them physically on par with Hollows so that they can battle on equal grounds.
Mod-Souls were produced as a part of Project Spearhead to bridge the gap between Hollows and Shinigami. This is because Hollows usually are much more numerous than Shinigami. The Mod-Souls are super versatile and varied in their abilities and can be categorised into different types.
Take for example, a Mod-Soul may have the ability to run many times faster than an ordinary human and in a different instance, another Mod-Soul may be many times stronger than normal.
Most Notable Mod-Soul Character in Bleach?
Kon, the Mod-Soul who accidentally ended up in Ichigo’s possession, is one very notable character from Bleach. He has enhanced leg-strength, which makes him an Underpod type of Mod-Soul.
Other Mod-Soul characters include Ririn, Nova and Cloud. They are not featured in the manga, and are exclusively designed for its anime counterpart. Being filler characters though, they’re not very important to the plot and also don’t have a tragic backstory like Kon.
How did Mod-Souls Originate?
The Mod-Souls, just like regular artificial souls, are placed in tiny, candy-like orbs. However, they were originally intended to be placed into corpses so that they would act as soldiers to fight the Hollows. Accordingly, they are also more independent compared to regular artificial souls.
The Mod-Souls were wiped out after the experiment stopped due to ethical reasons. Their existence became considered problematic because human corpses were being used as weapons against Hollows. Kon somehow got mixed up into a batch of Gikongan that contained normal artificial souls and shipped to Kisuke Urahara’s shop. This is where Ichigo and Rukia got hold of him and unknowingly let him loose.
Even though the Soul Society had announced an order to erase all remaining modified souls, Rukia and Ichigo still kept Kon and placed him into the body of a lion plushie. They use Kon whenever they need to possess Ichigo’s body, when his soul gets expelled from his body so that he can go off to fight as a Shinigami.