Chapter Text
When beginning your soul reaper training, you go through a series of lessons. The main being Hollow 101. You learn many things from how to defeat a Hollow and Hollow Ranks. There are low grade Hollows, mid grade Hollows and high grade Hollows.
Low grade hollows are hollows that soul reapers fight on a daily basis. These Hollow types usually gain their strength by preying on new, weakminded souls. They are uncaring about the amount of soul pressure within said soul only wanting to grow stronger.
Mid grade Hollows have similar traits to low grade Hollows. The only difference is these Hollows became as such shortly after they died. Murderers, criminals, hateful people etc. They all became mid grade Hollows shortly after dying and only became stronger the longer they continued the crimes they committed before death.
High grade Hollows are amongst the strongest of of Hollows. Although it is possible that a mid grade Hollow will evolve into a high grade Hollows, the majority of high grade Hollows are simply that. High Grade Hollows. They didn’t get turned into a Hollow nor did they eat souls to gain their strength. Nor did they become who they are based on past digressions. High grade Hollows are created from hate. Whether it’s from a living person or a soul, as long as there is strong hate, high grade Hollows appear. It is very rare for a soul to become a high grade Hollow but if they harbour enough hate or self pity within them, it can happen.
However what many do not know, is that there are Hollows that have been turned into humans. Nor do they know that there are hollow born children. These type of Hollows are considered Special High Grade or SHG Hollows. These types are rare but extremely dangerous. Though they may look human, they think like Hollows. They only want to feed on souls with a high spiritual power.
Another thing to know is that you should never confuse human born Hollows to human made Hollows. Although they look the same there is a distinct difference. They may look the same, but human made Hollows or Arrancars, gain their power from their masks being removed (Whilst also having a remnant of that mask to show they were once Hollows). Human born Hollows have their powers from birth and are known to be stronger than an Arrancar.
-Hollow Types, Hollows and Hollowfication, Obi Chiyako of the Research and Development Institute