In the world of ISEKAI: The Otherworlder’s Heir, magic is neither arbitrary nor universal. It follows precise rules and is structured around two major families, fundamentally opposed in the way they perceive power and act upon reality.
Mana-based magic — Transcending the Laws of the World
Mana-based magic is based on the use of magicules, energetic particles that bind naturally to elements of the same nature. For example, aqueous magicules possess an innate affinity with water molecules. They are found almost everywhere: in the air, within matter itself, among magical beings, and even condensed within certain rare minerals.
To channel this diffuse energy, practitioners rely on complex structures. Incantatory formulas, words of power, engraved circles, and material supports—such as artifacts and scrolls—serve to organize, combine, and stimulate magicules. The goal is to produce effects that are powerful, precise, and, in some cases, long-lasting.
Unlike its natural counterpart,mana-based magic offers remarkable freedom, but at a steep price: the more complex or devastating a spell becomes, the more its cost, difficulty, and inherent risks increase exponentially.
As with natural magic, it is also possible to draw magicules directly from the surrounding environment. This principle explains the existence of magical vectors—scrolls, artifacts, and enchanted devices—capable of amplifying or channeling this energy to produce magical effects without relying solely on the practitioner’s personal reserves.
Ethereal Magic — Shaping What Already Exists
Natural magic, known as ethereal magic, allows direct action upon the very structure of the elements themselves.
It draws upon the energy inherent in matter and requires a direct, almost instinctive connection with the element being manipulated—air, fire, water, earth, or their combinations. No incantations are spoken, no circles traced: mastery depends instead on a clear mental vision of the desired effect, inherited from an ancient power that binds the natural elements to its bearer.
Among humans, this form of magic is acquired through breath control, movement, and rigorous training, comparable to the discipline of martial arts.
The greatest strength of ethereal magic lies in its nature: it is not an indirect manipulation, but a direct authority over the structure of reality itself.
Its limitation, however, lies in its transmission. Originating from a mythical creature, this ancient magic is not passed down through heredity in the conventional sense. Only the female firstborn of a lineage inherit it at birth.
A formidable form of magic, therefore—but one that demands exceptional discipline.
Magicules — The Energetic Foundation of Mana
A Measurable, Omnipresent, but Finite Resource
The Great Land rests upon an energetic lattice composed of subtle particles known as magicules. These form an omnipresent field, comparable to an invisible atmosphere, whose variations in frequency determine elemental affinities. The study of magicules is a central discipline in understanding magical phenomena and arcane practices.
Nature and Classification of Magicules
Magicules vibrate at distinct frequencies, each associated with a fundamental element: fire, water, earth, air, light, and darkness. The dichotomy between light and darkness should not be interpreted as a moral opposition. Rather, it reflects the readability of the effects produced.
Healing magic, for instance, is classified under light because its results are immediately beneficial and transparent. Conversely, magic that imposes constraints—such as restraining an opponent’s movements—falls under darkness, even when its ultimate purpose may be considered just or protective.
Energy Reservoirs
Every magical being possesses a personal reservoir of magicules, the capacity of which varies according to the individual’s nature and potential. Dragons, for example, command astronomical reserves, vastly exceeding those of other creatures.
In addition to this internal reserve, an environmental reservoir exists within the air, the soil, and places saturated with energy. Ancient forests, crystalline mountains, and sacred ruins are notable loci where magicule density reaches exceptional levels.
Accessing the Environmental Reservoir
Under certain conditions, a mage may draw directly from the surrounding reservoir. While immensely powerful, this practice requires strict control to avoid energetic overload. Novices—often reckless—risk fainting or physical disturbances, leading masters to refer to such apprentices as “leaking barrels.”
Controlled access to the environmental reservoir remains a major field of research within magical academies, where scholars seek to define tolerance thresholds and develop reliable methods of regulation.
The Influence of Vespera
Vespera, the mysterious moon, exerts a decisive influence over the flow of magicules. During certain periods of proximity, it intensifies the ambient energy density and significantly amplifies spell potency.
The Nights of Vespera are renowned for spectacular duels, heightened rituals, and romances steeped in dramatic aura. Some accounts even claim that, beneath its silvery glow, human interactions—whether emotional or sensual—are tinged with a subtle magic, lending extraordinary intensity to even the simplest gestures.