The Spirit World (Reikai) has a system in which they rank all beings within the three worlds, including the Living (Ningenkai) and Demon Worlds (Makai). These ranks are given based on the being's physical abilities (strength, speed, etc.) as well as the amount of spirit/demon energy they possess. They are separated into six classes, from weakest (E-class) to strongest (S-class), with three tiers (upper, mid, and lower) typically in each one.
Classes[]
E Class[]
The weakest class of all. Demons of this strength aren't strong or smart but they are incredibly violent. However, their strength is just above that of the average human. Most humans and Spirit World residents fall under this category.
D Class[]
The second to lowest class. Like E-class demons, they usually aren't very intelligent (with few exceptions) or exceptionally powerful; but their strength and endurance is super-human compared to an average human. However, compared to most demons they are very weak. According to Koenma, Hiei was an Upper D-class demon when he first fought Yusuke. The strongest humans with spiritual awareness in the world are all D-class.
C Class[]
This is about average strength for most demons. They are much stronger than E and D classes, but their power pales in comparison to the stronger classes. These demons are very common and are relatively abundant in both the Human and Demon worlds. These beings are capable of tremendous feats of strength and speed, far beyond what even the strongest normal humans are capable, including moving faster than the eye can follow and withstanding falls into acid. The Saint Beasts (Genbu, Byakko, Seiryu, Suzaku), as well as most of the demons in the Dark Tournament, all fall within this class of demons.
B Class[]
This class is where the strength level skyrockets and is the beginning of the upper class demon power levels, where the difference between the previous classes is absolutely enormous. B class demons are far more powerful than C class demons, but they still can't compete with the higher classes. This is, in most cases, the strongest class of demon that can be found in the Human World, as any higher class can't pass through the Kekkai barrier net between the human and demon worlds. The only time a higher class demon will be found in the Human World is if the Barrier is down or a higher class of demon wears an organic device that downgrades their power, as Hokushin did when he first met Yusuke. According to Koenma, Younger Toguro was an upper B-Class demon when he fought Yusuke at the Dark Tournament.
A Class[]
The second to highest class, A-class strength level are almost exclusive to Demon World while the Kekkai barrier is up; the only exceptions are if a human attains this strength, a demon achieves this level in Human World, or if the barrier is destroyed and demons with this power can traverse to the Human World. Prior to the Kekkai barrier's removal, A-class demons could not move between the worlds without aid. While exceptionally powerful and rare in the Human World, they are relatively common in the Demon World. However, compared to the power of an S-Class demon they are very weak; so weak in fact that they are used as mere foot soldiers of the Three Kings. King Yama (Enma) and his soldiers, the Special Defense Force, as well as Yakumo and the Meikai gods, are all ranked within this class.
S Class[]
S class demons are the highest class. They are so strong that even a "low" S class' strength can completely devastate a large area. In the Demon World, they are rare; with only about twenty individuals ever known by name. It is extremely rare for even an A-Class to achieve this level, however it has been observed that a strong A-class could achieve upper S-class in less than two years. Sensui's full power was said to be at this level, as was Yusuke's when he came back to life as a demon. Kurama and Hiei also reach the S Class during the Three Kings saga.
Upper S Class[]
The strongest known level of power in the series. Demons of this caliber are extremely rare, with only Yomi, Mukuro, Raizen, and Raizen's old sparring partners as the only beings known to have reached this level. However, it is implied by Kurama that more demons of this caliber may exist in seclusion within the deepest depths of Makai. Demons who possess this strength are said to be godlike in power and are so strong that they are unable to exist within Ningenkai without affecting the fabric of reality. It is implied that anyone with a power level of over 200,000 is Upper S Class.
Trivia[]
- S and E classes are very rare. E class is so weak that they simply don't last long and technically don't even show up on the Spirit World's chart. S class, on the other hand, are the opposite. Their strength is so rare that even Spirit Worlds' elite soldiers don't know about them.
- In both the anime and manga, C Class has the biggest roster of characters in the series.
- The A class is the third most rarely seen class behind E and S, as most B class demons do not make it to A class, and some of the time when they do, they rapidly progress to S. With some individuals, it only takes a few months or years to reach lower S Class levels once in A class, with proper training from strong individuals.
- Most higher-level demons consider the Spirit World class system to be insulting as the S class category merely refers to demons they do not have the power to fight or stop. Also, demons they consider S class range from simple foot soldiers to demons that are considered to be like gods. Because of this, the powerful upper S Class demons do not like being put in the same category as their underlings.