With the power system in Hell's Paradise: Jigokuraku slowly being revealed to viewers of the anime, there have been some notable similarities to the power systems of various other shōnen titles; however, the closest similarities have been drawn between Yūji Kaku's Hell's Paradise: Jigokuraku and certain elements of Togashi Yoshihiro's Hunter x Hunter. The power of Tao currently being explored in Hell's Paradise: Jigokuraku seems to feature several similarities to the Nen power system of the Hunter x Hunter universe.
What many fans making the connection don't know; however, is that the similarities come not of direct inspiration from Hunter x Hunter, but rather from the exploration of the same concept in different universes. What are the similarities between Nen and Tao, and why are they so glaring?
Trope Carousel
Shōnen anime is famous for its self-referential nature; which means that titles have a tendency to interact with each other and refer back to each other, perpetuating and evolving various trends and devices in ways that show direct influence between works. The reuse and re-purposing of concepts in anime in general extends beyond stories from the same or similar media, and even goes into books, movies, music, mythology, philosophy and of course, religion. Mythology, religion and legend inform a large part of the anime encountered particularly in the subgenre of battle shōnen, and in the case of Hell's Paradise: Jigokuraku, Chinese mythology, Japanese mythology, as well as Taoist and Buddhist concepts are married with a premise inspired by a western novel. The religious and philosophical elements taken from Taoism and Buddhism are reflected in the construction of Shinsenkyō, as well as the power concept used in the series.
There are countless anime series, franchises and titles that appear similar only because they share the same inspiration, and sometimes, that inspiration happens to be something as traceable as myth and legend. Examples of this include the pervasive wuxia element found in influential titles like the Dragon Ball franchise, which is in turn based on the Chinese novel Journey to the West. While various instances of "Sun Wukong" (Goku) are found in anime, none are accused of copying Dragon Ball in particular when the character is invoked because of his pervasive depiction in fiction. In any case, just like in Hell's Paradise: Jigokuraku, Hunter x Hunter characters have to train hard in a number of pivotal realms before they can gain a good level of Nen mastery.
Cosmic Order
Concepts like the Yin-Yang, cosmic order and the manipulation of some kind of primordial necessary force of reality are everywhere in anime, manga and beyond, and many of the specific inspirations that led to the development of Nen as a power system in Hunter x Hunter are the same ones drawn upon in the Tao used by characters in Hell's Paradise: Jigokuraku. Beyond that, inexplicable similarities between entire mythologies in human history have been used almost as a binder between cultures in time. Similarly, the "essence of life" is understood differently and known by different names, a concept as primary as life-energy being manipulated to grant supernatural power is found in various works of fiction inspired by a single instance of such a concept, or an unintelligible combination of various instances as seen on the island of Kotaku in Hell's Paradise: Jigokuraku. The series makes its Buddhist/Taoist inspirations clear through its extensive introduction of concepts from both religions/philosophies and retention of their real-life names.
Wuxing is the ancient Chinese concept of the five agents of change, the five "elemental" points in the cycle of reality that feed into each other or act to each other's detriment. The elements are Wood, Fire, Earth, Metal and Water and in this order, the previous element is conducive to the next; however, like in Pokémon, each attribute has its bane and boon. Wood feeds Fire, but thwarts Earth; Fire feeds Earth, but thwarts Metal; Earth feeds Metal, but thwarts Water; Metal feeds Water, but thwarts Wood and Water feeds Wood, and thwarts the obvious opposite, Fire. In similar fashion, Nen-users have their native types and a set level of compatibility with the others based on a similar, wuxing-esque relationship between the six types: Conjuration, Manipulation, Emission, Transmutation, Enhancement, and Specialization, each of which dictate what a character's Nen does.
Infinite Eight
This is further complicated by the fact that the concept informing this cycle is Yin-Yang, and depending on the point in the cycle, different hybridisations of the main five are divined. How this is done differs depending on the application of the wuxing concept; however, since Hell's Paradise: Jigokuraku makes reference to the I Ching, the understanding of these interstitial states that we'll develop will be those found in that text. This is important because of how the Hunter x Hunter universe interprets its application of this concept which gives rise to the Nen Types. Hell's Paradise: Jigokuraku uses typing through applying the elements to different characters, giving them different types of Tao. When looking at wuxing from the I Ching's perspective, there are two possible states of each element: negative and positive; Yin and Yang. This gives rise to the aforementioned hybridisations, which are represented with something called the Bagua – Eight Trigrams.
The Eight Trigrams are a set of eight symbols that are representative of the eight fundamental principles of reality with each being represented with three horizontal lines which are either broken or unbroken, representative of Yin and Yang respectively. Since each elemental phase has two extreme states, the number of possible combinations increases the number of permutations to 64 aspects known as hexagrams. For example, the trigram for Earth is three broken lines, while that of Heaven is three unbroken lines. When they meet, these two aspects form hexagram 11, named "tài", which is interpreted as "move in a state of harmony/tranquility". Hunter x Hunter's Nen system allows for affinity to one of six baseline expressions of Nen, with some level of compatibility with other types based on the relationship between these types, and one's specific position on the interconnected cycle of Nen types. Like Hunter x Hunter, Jigokuraku expresses a similar mechanic in its Tao power system due to the similarity of inspiration that both have interpreted differently for the sake of different narratives.