Higa Takeru

Higa Takeru is the junior colleague of Akihiko Kayaba, Nobuyuki Sugou, and Rinko Koujiro in the Shigemura Laboratory at Tōto Institute of Technology.

He later becomes one of the core engineers at Rath, responsible for the research and maintenance of the Underworld and the Soul Translator system.

He is described as short and slight in build, wearing rugged round glasses, with spiky short blond hair and anime-character T‑shirts.

His casual speech pattern, laid-back otaku vibe, and habit of calling his superior Seijirou Kikuoka “Kiku-san” make him seem far from a stereotypical serious scientist.

Despite this appearance, Higa is a genuine prodigy, recording an IQ of around 140.

His competence and creativity place him at the center of several critical technological breakthroughs in the series.

He first appears chronologically in the Accel World crossover story "Versus" (included in Accel World Volume 10), and later in the Sword Art Online: Alicization arc.

His role grows significantly during the Ocean Turtle incident and the events following the War of Underworld.

Higa’s first-person pronoun is “boku,” reflecting a relatively mild and approachable personality.

He is informal with colleagues, friendly, and somewhat flippant, often speaking in a light, relaxed tone.

On the surface he comes across as a typical geek: anime fan, casual clothes, and an almost playful attitude toward cutting-edge technology.

Underneath that, however, he shows strong professional ethics and a serious awareness of the consequences of his research.

Unlike Nobuyuki Sugou, who twisted his inferiority to Akihiko Kayaba into outright villainy, Higa remains psychologically stable and morally grounded.

He can admire genius without losing his own ethical compass.

Higa genuinely respects Akihiko Kayaba as a scientist, even while condemning the atrocities of the Sword Art Online incident.

He also harbors a quiet, unspoken crush on Rinko Koujiro, Kayaba’s lover, but never confesses because he feels he cannot surpass Kayaba in her eyes.

Initially Higa is capable of viewing artificial Fluctlights as “objects” or “products” of his work.

Over time, direct exposure to the Underworld and its inhabitants forces him to reconsider this detached stance and see them as something much more.

Higa joins Rath’s top-secret Project Alicization, not out of nationalistic fervor, but from a pragmatic and somewhat idealistic hope.

He believes that even if war can never be completely erased from the world, it might at least be reshaped into a form where human beings no longer have to die on the battlefield.

A major part of this motivation comes from a personal tragedy in his student days.

A close Korean friend of his was conscripted, dispatched to Iraq, and killed in a suicide bombing attack during military service.

This loss makes Higa deeply aware of the cost of conventional warfare.

The idea of replacing human soldiers with highly autonomous, human-like AI combat units seems to him a potential way to prevent tragedies like his friend’s death.

Even so, he begins the project thinking mostly in terms of technology and strategy.

For him, the Underworld initially looks like a sophisticated test bed for AI rather than a place full of truly “living” beings.

Higa is one of the main engineers overseeing the Underworld, the vast virtual realm inhabited by artificial Fluctlights.

He is heavily involved in both the design and live monitoring of this world as it rapidly evolves.

He works with Rath’s flagship device, the Soul Translator (STL), which reads and writes to Fluctlights—digital copies of human souls.

Through the STL, he observes how the Underworld’s inhabitants grow, interact, and develop increasingly complex societies and personalities.

At Rath, Higa also develops physical bodies for Fluctlights to operate in the real world.

These are known as Electroactive Muscle Operative Machines, or E.M.O.M units, intended to bridge the gap between virtual beings and physical action.

Initially, Higa considers the Underworld and its people as advanced tools or experimental constructs.

However, events later force him to confront how indistinguishable they are from real humans in the ways that matter most.

Higa is credited with the development of E.M.O.M (Electroactive Muscle Operative Machine) bodies.

These are humanoid platforms that allow Fluctlights to act and move in the real world.

The first unit, known as the No. 1 machine, includes a dedicated balancer for posture control, making it somewhat bulky and mechanical-looking.

Despite its robust appearance, it provides a crucial test platform to verify Fluctlight-controlled locomotion in a physical environment.

The second unit, the No. 2 machine, is built on a different philosophy.

It omits a dedicated balancer, relying instead on the installed Fluctlight for posture and motion control, which allows a much more slender, human-like design.

Higa also casually gives them nicknames derived from their model numbers, showing his playful side.

The No. 1 unit is “Ichiemon,” and the No. 2 unit is “Niemon,” joke names that make Asuna Yuuki roll her eyes because of how simplistic they are.

Later in the story, these two E.M.O.M units become vital to the plot rather than remaining mere test devices.

They play important roles in bridging the Underworld and the real world at a critical juncture.

Following the main conflict, a newly constructed No. 3 E.M.O.M is assigned to Alice Zuberg.

It can be charged via an ordinary household power outlet but cannot eat or drink, a limitation that Alice strongly pressures Higa to fix.

Alice is blunt enough to call Higa simply “Higa,” without honorifics, underscoring their direct and somewhat exasperated dynamic.

In turn, he takes her demands seriously, recognizing that for a Fluctlight trying to live among humans, such details matter.

Higa maintains a professional yet informal relationship with Seijirou Kikuoka, the man leading Project Alicization from the shadows.

He calls him “Kiku-san,” a very casual form of address, which indicates both familiarity and a certain irreverence.

He deeply respects Akihiko Kayaba’s brilliance in system design and virtual reality engineering.

While he cannot condone the Sword Art Online mass murder, he cannot deny that Kayaba reshaped the whole field in ways no one else did.

With Rinko Koujiro, Higa’s feelings are more personal and quietly tragic.

He admires her as a scientist and woman, yet believes he can never outshine Kayaba in her heart, so he keeps his affection to himself.

Higa’s interactions with Kazuto Kirigaya (Kirito) and Asuna Yuuki are mostly as a behind-the-scenes supporter.

He is impressed by how they treat the people of the Underworld not as non-playable characters but as real individuals.

His perspective on artificial Fluctlights is strongly influenced by Eugeo, who manages to speak to Kirito even after his death within the Underworld.

He is also affected by the existence of Quinella, who manages to brainwash a real-world human, Yanai, proving just how powerful and autonomous a Fluctlight can become.

He later works closely with Alice Zuberg as she adjusts to living in the real world in an E.M.O.M body.

Her straightforward demands and human-like presence underline for him just how far their “AI” has gone beyond simple code.

During the Ocean Turtle attack, Higa is stationed in the facility where the Underworld’s core systems are located.

He plays a crucial role in keeping the STL network running while the base is under siege.

At a critical moment, Yanai betrays Rath and injures Higa.

Despite being wounded, Higa manages to connect the STL lines used by Kirito, Asuna Yuuki, Leafa, and Shino Asada to the Underworld.

He also links the residual Fluctlight of Eugeo, preserved in the main visualizer, into Kirito’s STL session.

This act becomes a key trigger for Kirito’s return to consciousness within the Underworld.

Higa’s quick thinking and technical expertise directly contribute to Kirito’s recovery and the final stages of the War of Underworld.

Without his intervention, the heroes might not have reunited or survived the crisis.

Throughout the incident, he is forced to confront the reality that these are not just “programs” or “data sets.”

The choices he makes treat the Fluctlights as real lives worth risking his own safety for.

At the beginning of his involvement, Higa’s stance is similar to that of Kikuoka: artificial Fluctlights are sophisticated creations, but still creations.

He sees them as tools for a new kind of warfare rather than independent persons.

Several events overturn this belief.

First, Quinella, an artificial Fluctlight, manages to brainwash Yanai, a real-world human, an outcome that demonstrates her terrifying autonomy and will.

Second, Eugeo dies within the Underworld yet continues to support Kirito afterward by reaching out from what remains of his Fluctlight.

The emotional and psychological weight of this interaction is indistinguishable from what a “real” human friend would do.

Third, he witnesses the existence of “Star King Kirito” and “Star Queen Asuna,” versions of Kirito and Asuna who live for approximately 200 years inside the Underworld.

Their experiences, memories, and personalities develop in ways that could not be dismissed as simple scripted behavior.

Confronted with these facts, Higa concludes that Project Alicization has gone far beyond ordinary AI development.

He realizes that they have essentially created a new form of life—a digital humanity that can think, feel, and grow.

He also understands that a major reason their research advanced so dramatically was the attitude of Kirito and his friends.

By treating the people of the Underworld as real humans rather than as NPCs, they allowed those Fluctlights to develop in ways that pure experimental control never would have achieved.

This shift in perspective profoundly changes how Higa views his responsibilities.

He moves from seeing himself as a designer of tools to a caretaker of an entire world.

After the main conflict and the War of Underworld, the existence of “Star King Kirito” becomes a sensitive issue.

Star King Kirito is the Kirito who spent about 200 years in the Underworld alongside Star Queen Asuna, a version who is immensely experienced and powerful from a Fluctlight standpoint.

For security and ethical reasons, there is an intention to erase the Fluctlight of Star King Kirito.

Higa, however, feels a strong reluctance to simply destroy such a unique and evolved being.

He secretly makes a copy of Star King Kirito’s Fluctlight before its intended deletion.

He keeps this copy in his possession, fully aware of the risks and responsibilities it entails.

At some point, the copied Kirito asks Higa to search for a copy of Akihiko Kayaba.

The goal is to enlist Kayaba’s help in protecting the Underworld from future threats.

Higa is fascinated by the idea of seeing what might unfold when a duplicated Kayaba meets the Star King Kirito.

His scientific curiosity and emotional investment in both figures push him to cooperate with this unconventional plan.

Following the Alicization arc, Higa is shown sheltering a certain individual, hinting at his ongoing involvement in hidden aspects of the story.

This suggests that his work with Fluctlights, the Underworld, and key figures like Kayaba and Kirito is far from over.

Through all of these actions, Higa balances his identity as a playful otaku engineer with the sobriety of someone who realizes he may have helped create an entirely new civilization.