With Rukia Kuchiki to show him the ropes, Ichigo learns how to use his Zanpakuto to defeat Hollows and liberate trapped souls by using Konsō to guide them safely to Seireitei. Ichigo has been so in tune with the spirit world that he allegedly could not tell the difference in his youth, and he had met his fair share of Hollows before even knowing what they were. Here are some helpful details about the Spirit World that would have made Ichigo's life a little easier.
Not everyone is fortunate enough to experience a clean death, and some souls (with unfinished business) find themselves tethered to their dead bodies by a Chain of Fate, trapped for all eternity. In many instances, this Chain may become severed, and the soul is then able to move about freely.
However, the Chain of Fate does not disappear but rather corrodes over time, draining the humanity out of the Plus in the process. If left too long, these Pluses will transform into Hollows as their Chain of Fate withers from existence. Thank goodness for Shinigami such as Ichigo, who seek out Pluses hoping to perform the Konsō ceremony on the poor souls before it is too late.
The Bleach storyline is heavily dependent on the concept of reincarnation which, as most may already know, involves a flow of souls in an endless cycle between living and dead (much like Newton's Law of Conservation of Energy).
In theory, when a person dies, their spirit moves on to the spirit realm to live out the remainder of their afterlife in Rukongai or Seiretei, until they die and are then reborn as a human. Those wicked enough to end up in Hell are not candidates for reincarnation, however, the Bleach One-Shot Manga suggests that this might not actually be the case...
When a Shinigami discovers a lost soul trapped within the human realm, they need to perform a ritual to help the transition into Soul Society go smoothly. Konsō, which literally translates to 'Soul Funeral', describes the process whereby a Shinigami touches the hilt of their Zanpakuto to the Plus' forehead, marking them with a glowing emblem. The Plus is then able to travel over to Soul Society after dissolving into a radiating blue puddle of energy, leaving a Jigokuchō (Hell Butterfly) in its wake.
It is said that if a Zanpakuto is held to a Plus' head for an extended period of time, it will cause immeasurable pain, although why a Soul Reaper would do this is anyone's guess. Depending on the soul's level of Reiatsu (spirit energy), they will be reborn into either Rukongai to live out a 'regular' afterlife, or Seireitei where they will train to become Soul Reapers themselves.
In the Thousand Year-Blood War Arc, a new concept of Konsō Reisai was introduced, shocking viewers around the world. This ritual speaks of the darker side of Seireitei, whereby a Hollow is hunted down in a ceremony known as Jogimen Reibaku and purified at the grave site of a fallen hero. The event usually only takes place twelve years after the death of a Gotei 13 member, and supposedly allows the deceased Shinigami's energy to be safely dispersed throughout Soul Society. However, the true reason for this ritual is much more sinister. It turns out that the Reiatsu of a Shinigami Captain is too powerful and dense to be reabsorbed into Seireitei, and instead their spirit is cast into Hell - for everyone's safety.
Fans' minds are blown at the thought of a highly respected Captain such as Yamamoto or Unohana, after spending their afterlives dedicated to saving others, are actually being damned to hell- and by their closest companions no less. The Soul Cycle system is clearly broken if this is to be the reward for a lifetime of servitude. However, as mentioned before, the Bleach One-Shot Manga provides the possibility of the Hell bound spirits returning to the living world - good news for the Captains, but disastrous for pretty much everyone else.