Mei watched her father cautiously. The man shifted into a long stance. Against his own daughter he would show no mercy. Mei adjusted to a shorter stance. The pair faced one another in a 10 by 10 metre room, unfurnished with bare metal walls and floors, small cameras built into the roof taking in the entire scene. Father and daughter wore simple gi. The katana in scabbard they held at their side were real blades. Both had progressed past the stage of using habiki.

Ryoma had ever advantage over his daughter. Thought she was tall for her age, Mei was still only eight years old and had the build, reach and muscle strength of a child. Ryoma was more than twenty years her senior and continued to maintain his peak fitness. He had spent more years practicing the Hokushin-Itto-Ryu than his daughter had lived. He was her instructor.

This was why he treated her with all deferential respect and caution.

At an unspoken signal the two burst into motion. Raiden drew first, relying on his mastery of iajutsu to end the fight quickly. The scabbard fell to the floor as he advanced two steps, blade a quicksilver blur he whipped it up and brought it down in one clean stroke. Mei took a half step to one side, drawing her katana and keeping the scabbard to gently deflect the blow. Now down his one advantage of being the first to strike, Ryoma was forced to fight his daughter in lethal earnest. The man's form and technique were perfect. Each motion, each placement of the foot, each shift of his bodies weight was driven toward the singular goal of defeating his daughter. He kept his movement about the room minimal, dominating the area through size and strength. Mei was the very embodiment of the Hokushin-Itto-Ryu. Offence and defence in one action. Her scabbard she used to deflect and guide Ryoma's blade. With her katana she felt out his defences. Probing mercilessly and with intuitive understanding. To an outsider it was like viewing two prodigies at their highest level. The Raiden family moved so fast it was hard to keep up. What looked to be a lethal strike was parried, blocked or deflected at the last moment. What might have been a misstep turned into a roll to better position for an incisive flurry of blows. The sound of steel on steel rung throughout the room. A bell for the paragons of their art.

Mei wasn't sure why they were duelling yet again. For the last few months she had come to the facility twice a week. They would test her in all sorts of strange ways. Running, sprinting, jumping, weightlifting, moving across obstacle courses with perfect balance. On and on they wanted to test her. For the last month it had been Hokushin-Itto-Ryu duelling. Mei had been taught by her father since she was old enough to hold a training bokuto. She knew more about the koryu at 5 than most people had at 20. Ryoma was an exacting teacher. But one who never pushed his pupil beyond her current limit. It had been to his delight that Mei was a prodigy.

Or had been until the incident nearly a year ago. After retreating into herself the girl had shown little of the previous controlled and composed demeanour. She hadn't returned to the dojo once. It was upon the instruction of her physicians that she picked up a blade for the first time in a year. The weight and balance alien to her. Uncomfortable and unfamiliar.

The first duel between father and daughter awoke something in Mei. She could feel it in her heart even now. A pulse that heightened perception and quickened movement. A pulse alongside blood. A crackling jolt that mirrored each strike, stroke and deflection. In this moment when Mei was in control she felt alive. Ryoma gave his daughter no ground. Blade lashing out in a series of overhead strikes. Each was artfully knocked away. Mei used the opportunity to slip forward, utilising her short stature to make horizontal strokes ineffective, lashing out teasingly with her blade. Ryoma remained in control but took a step back. He rained down several more blows. The clang of steel grew louder.

Mei didn't want to lose. She hated it. She didn't want to be weak. She hated it. Mei would be strong. Nobody would take that strength from her. She would be strong and command her own life. She had lost control before. She had been weak before. But no more. She would not be backed into a corner and broken because she was weak.

In this moment Mei gave in to the thing that lurked just behind her eyes and wore a smile that didn't belong to her. Observers looking through cameras that recorded all manner of spectrum marvelled at the response. Mei's body heat dropped one whole degree. The electromagnetic spectrum thrummed with unseen crackles and sparks. Honkai energy, previously soupy within her small frame, surged to life and formed arcs of power between the regions of her body. On the visible spectrum nothing had changed. But Ryoma knew it wasn't his daughter he was facing anymore. Mei oozed like quicksilver into a more aggressive stance. She discarded the scabbard and held her katana patiently in both hands. Her eyes were clear and expression detached. There was no kindness in her next flurry of attacks. Each contained the aggression and merciless power of a dragon. In four seconds Mei was inside Ryoma's guard. Her blade was so fast the outside observers would need to review the highspeed footage to understand just what had happened. It ended with Mei behind her father, katana held high enough to press the tip gently against his throat.

Mei was back in control. She gently lowered her blade, turned and bowed to her father. Ryoma did so in kind. He walked over to one corner of the room and picked up a bottle of water. The man pressed a finger against the intercom and took sips in between breaks in conversation with someone on the outside. Mei walked over, picked up her scabbard and sheathed the katana. She walked back to her corner and picked up the drink bottle. The sweaty girl took a mouthful and slowly swallowed. Her body felt tingly again. Like a hand she had sat on for too long and was now numb. A hand that didn't belong to her. That was happening more and more lately. She put down the bottle and picked up her katana. Popped it partially out of the scabbard to check for nicks or scratches. In the steel reflection she saw a pair of crimson eyes looking over her shoulder.

"You said you wouldn't bother me here," Mei whispered.

"Well you asked for me," her Twin replied. "What else could I do?"

Discomfort prickled up Mei's spine. She took her blade and walked up against the wall. With her back to her father she hoped he wouldn't see her lips moving. In the last few months Mei had learnt how to mask her conversations. The awkward looks she received from others had taught the girl the value of discretion. Mei held the blade a little higher and changed the angle. Her Twin's sardonic grin appeared in the steel. Those intense crimson eyes that saw past every lie. The crinkles on the edges that said she felt the same pain that Mei did. Only that her Twin chose to deal with that pain in a different manner.

"They're testing you again," her Twin observed. "But then again it is not you they are testing. They want to test me. You are just baggage along for the ride."

Mei wanted to rebuke her Twin. She didn't like the cruel words they uttered. But she also knew they were right. Unseen hands pressed on Mei's shoulders. Static fingers pressed down as though trying to reassure.

"You want to be strong. Yet you still call on me. You should make this power your own. And yours alone. They want to understand you. They'll pick you apart piece by piece if possible."

Mei sheathed her blade with a final metal clack. The taunting laughter of her Twin filled her ears.

"Maybe one day you'll be strong enough."

"Mei. Again," Ryoma ordered.

"Yes, Oto-sama."

"I am beginning to reach the upper limits of my own self-education, Dr Schwarz."

"Honestly, I'm in awe you have followed me up to this point."

Dr Schwarz gestured with his coffee cup in respect before downing the contents. Hanakawa was having a one-on-one meeting with the man. Several months into Project-MEI and he had finally reported his results leading to a critical insight. Raiden Ryoma was busy that morning training with his daughter so it fell to Hanakawa to listen to and document a brief that could be tabled. If the Chairman approved of the brief then further funding would be put into the engineer's research. The pair had the main meeting room to themselves. Hanakawa hadn't deemed it necessary to activate the white-noise systems yet.

"Can I assume you've seen some of the genetic algorithm games online that are all the rage?" the engineer asked.

Hanakawa shook her head once.

"They usually orientate around 2D creatures evolving the ability to walk. The user puts together a creature with a variable body structure; number of arms, legs, hand and feet. Then you hit the Evolve button. The genetic algorithm tests several permutations against the creature running away from a death flag. Of course the first generation will all going to die. So you hit the Evolve button again. The genetic algorithm tries again and again. Each Evolve changes the walking motion of your creature. Eventually one or more creatures will evolve with the right gait pattern to escape the death flag.

The idea is that you have a fixed goal and a certain number of weighted variables. Survive or die. It's a simple idea but demonstrates a much broader problem. Even something as seemingly simple as waking is not. Multiple generations before you get even close. What's weighted in your favour is that the algorithm knows the end goal. Escape the death flag."

Dr Schwarz tipped his free hand toward the thesis Hanakawa had been reading through. She had interspersed her reading with clarifying questions. A quarter of the way through the woman had stopped. Hanakawa, much like the resident genius Elijah Orr, had no formal tertiary training or education. She had applied to work for ME Corp as a secretary fresh out of High School. From there her impeccable work ethic, intuitive grasp of discretion and prescient acumen regarding anticipating her superior's needs had steadily led her up the corporate ladder. Now she worked directly under Chairman Raiden Ryoma. This had led her to studying multiple branches of business, science, sociology and more in her personal time. Raiden Ryoma was an exacting and demanding man. He had faith in Hanakawa to keep up with whatever was needed. The chairman trusted his right-hand woman implicitly.

Once the paper went into the territory of topoisomerases, gyrases, negative supercoiling and molecular logic circuit replication Hanakawa knew she was lost. This now led to the specialist's explanation and example of genetic algorithms.

"As I've said before, I'm a Honkai energy engineer with knowledge in biology. Which is why I can see the machinery at work."

The man leant back in his chair and stared up at the ceiling. He chose his next words with certain care.

"We know from the Soulium fragments that ME Corp recovered post Second Eruption that the people of the Previous Era were working on all manner of black project. They were desperate to find a way to stop the Honkai. Just like us. Desperation breeds all sorts of dangerous thoughts. I've searched the genetic database that Project-MEI has compiled. Just over one million human genomes. Each and every one of them one or two of the same sequences as Subject Mei. The placement always varies. I even checked monozygotic twins. Minor permutations that nobody ever noticed because they didn't know exactly where to look. not active. Not complete. But there. That goes against all conventional science we have observed in other species."

"You talked previously about this being incredibly well crafted machinery. So what do you believe is the intent?"

"For those online games the end goal is to walk fast enough to escape the death flag. What if instead the end goal was to survive the Honkai? That's an incredibly complex goal. Resistance to Honkai radiation sickness or perhaps even immunity. Increased base physiological and mental capabilities. Or even something more profound. Start hacking the laws of reality. It honestly scares me. You would need to scale your genetic algorithm accordingly. The complexity increases by several factors along with all the moving parts. The complexity of this machine. The engineering required borders on the realm of the theological. But someone did build it. We're looking at it in action right now. My theory is that the Previous Era built this machinery but ran out of time in the end. They couldn't test is. Or they were afraid to."

Hanakawa tugged on a loose feather of her boyish fringe. What the man was saying was starting to fall into place. A cold sense of awe and realisation tickled her fingertips. If the man was right. If the man wasn't mad. If he had seen into the minds of…

The woman did not like the possibilities. But much as the engineer had, she could see no other conclusion than the pragmatic one he was inevitably leading up toward.

"The Stigma is the single largest live medical trial ever attempted," she surmised. "Each one of us has this machinery built into us. Specific epigenetic pressures are the trigger."

The doctor began ticking off his fingers.

"Exposure to Honkai energy is certainly one of them. Probably psychological components such as stress or mania. There are other components I'm yet to pin down. Tailored chemical triggers. Novel energy type exposure. Maybe connections to Imaginary or Quantum spatial phenomenon. Perhaps the more boxes you tick the better the odds. It's so incredibly complex my head begins to hurt just thinking about the underlying mechanisms. Regardless, the end result is the same. Stigma is the ultimate algorithmic test. Is the combination of genetic sequences that make up your unique version of Stigma viable? If no, then radiation poisoning, zombification or a Honkai beast kills us. If yes, then that combination gives us whatever novel advantage necessary for us to survive. After that the machinery fully activates and begins conducting all the right adjustments to the surviving human. Hopefully this information can also be encoded as a dominant genetic trait to the gametes."

Dr Schwarz put down the coffee cup and scratched the back of his head.

"I conducted a test trial exposure of ten thousand blood samples to Honkai radiation. Monitored and observed reactions at a genetic level. The same results as the last batch of blood samples I tested. No genetic expression to match Subject Mei's. Complete cellular death. But looking through the debris of the negative supercoil I could find sequences matching some of the new proteins we have since categorised from Subject Mei. The machinery partially waking."

"How many people do you think have died due to Honkai radiation exposure over all of human civilisation?" Hanakawa asked the man.

"Pass. Too many to count."

"According to Schicksal records there are only two Natural Stigma. Of everybody that has ever been exposed to your proposed test only two variables have led to survival and been passed on to the next generation."

"And apparently they are two very different evolutionary adaptations to fighting the Honkai. The success rate of this Stigma project is so frighteningly low I think we'd have a better chance of solving the Fermi Paradox."

Fingers releasing her hair, Hanakawa began tapping several notes and orders into her tablet. A several-fold increase in the Schwarz's budget. Approval for discretionary spending up to ¥5 billion. Expansion of his research space and adjunct staff.

"Can I ask you something, Hanakawa?"

"Certainly."

"Why does Ryoma insist that we refer to his daughter as Subject Mei?"

"Human psychology. It dehumanises her. We need our researchers to not think of her as a person. Not the daughter of Ryoma-sama. We need your research to be pure and unfiltered. We are not Schicksal. She is treated very well. But ultimately Mei-ojou-chan is a test subject vital to the future of ME Corp."

A finger hovered above the final approval fingerprint scan. A curious thought. Pregnant with dark implications. Desperation breeds dangerous thoughts.

"The Stigma are an incalculable advantage to humanity," Hanakawa half-stated, half-asked. "Could you forcefully activate the mechanism? Attempt to give the species that sort of power?"

Schwarz let out a bark of laughter.

"Easily. Just detonate enough Honkai nuclear weapons to soak the planet in radiation. The only test is a live trial. It would be genocide. But you would find a few that survived."

The man chewed his cheek and stared back at the ceiling.

"I guess you could find ways to fine tune. Now that we know what a Natural Stigma looks like via Subject Mei you could do some minor retroviral engineering. Test to see if certain sequences present or absent compared against the Natural Stigma make a difference. Would still take an inhuman number of live trials. Could improve your odds. But it's a cost too steep. Humanity rejected Eugenics decades ago. Going down that path would make us worse than the Honkai."

A finger pressed against the authorisation scanner. Schwarz would go home to his family tonight. Hanakawa was thankful. Killing someone was something she found distasteful.

"But I could probably turn it off," the engineer ventured.

Hanakawa went cold. She slowly lifted her eyes.

"Turn it off?" she drew out the words

"Perhaps a better word might be suppress or seal it. The machinery is already active. But there are options."

"I heard before that this could not be done. That trying to block the Stigma genetic machinery failed."

"Several months of research opens other avenues. I expect that there are more instances of the Stigma partially awakening than records might otherwise show. But a partial activation would have it's own suite of complications that probably lead to death soon afterwards. An incomplete Stigma that kills through reasons not related directly to the Honkai. If I can find examples of incomplete activation I might be able to... no I'm getting ahead of myself. But it might be possible."

A soft smile crossed Hanakawa's lips. One missed by the doctor. She had a narrow thread of opportunity. Ryoma-sama would want to know.