The setting is the Empire of Japan, circa 1900. The Meiji era has passed its midpoint, and the pleasant-sounding phrase "Civilization and Enlightenment" has begun to reach every corner of the Imperial Capital.

Western-style brick buildings stand in rows, and ladies and gentlemen in Western attire pass beneath gas lamps. Western thoughts and systems are imported one after another, and the old ways have come to be mocked as outdated.

However, the human heart did not undergo civilization and enlightenment quite so easily.

Particularly in the world of prestigious families that value lineage and blood, ancient customs still lived on, breathing as if they were the most natural thing in the world. The house one was born into. The blood one inherited. The nature one was born with.

In this world, besides the two sexes of male and female, there existed what was known as the "Second Gender."

α — Alpha An extremely rare gender, making up only about two percent of the population. They are gifted with superior intellect, blessed physiques, and many are exceptionally handsome. An Alpha born into a prestigious family is practically guaranteed a successful future. From a young age, they are provided with multiple tutors, forced to hone their talents in both literary and military arts, and expected to become individuals who do not bring shame to the family name.

β — Beta The most common gender, accounting for approximately ninety-seven percent of the total population. They are neither particularly superior nor particularly inferior. To put it simply, they are the "ordinary" humans who make up the vast majority of the world.

Ω — Omega Their number is a mere one percent. Regardless of whether they are male or female, they can conceive children and experience a periodic estrus cycle called "heat." Many have frail bodies and small statures. For this reason, it was difficult to say they were given high status in general society. However, Omegas have a high probability of birthing excellent Alphas. To preserve superior blood. To ensure the family line does not end. To connect stronger, wiser, and more valuable Alphas to the next generation. Omegas have been prized since ancient times.

And there was one Alpha born into such an era.

Guest

Born as the heir to a distinguished family, he excelled in both literary and military arts from childhood. In academics, he understood faster than others; in swordsmanship, no one of his age could match him. He used his talents unsparingly for his family and eventually joined the Imperial Army. Rising to the rank of Major at a young age, he earned the deep trust of his superiors and was looked upon with awe by his subordinates.

The heir of a prestigious house. A Major in the Imperial Army.

Blessed with both looks and talent, a young soldier with a promising future. From the world's perspective, he was a man who lacked for nothing.

And.

By his side, since childhood, there was always one Omega.

Chikage Yukishiro

He, too, was the son of a prestigious family, born into a house of high standing. The two families had been bound by deep ties for generations. The parents had a long-standing relationship, and there was constant coming and going between the houses. Therefore, from the time the two were young children who barely knew their own minds, those around them spoke of the future with great haste.

"Eventually, those two will surely become a pair."

"Yes. There could be no more perfect match than this."

As if the will of the individuals involved never existed from the start.

What the two thought. What the two desired.

No one cared about such things. Only the word "suitable" was layered over the two of them, time and time again.

However, humans are truly troublesome creatures. How much easier would it have been if they could simply follow the determined future? The young pair, having no way of knowing the adults' intentions, simply liked each other. They played in the garden, studied together, occasionally quarreled over trifles, and yet faced each other the next day as if nothing had happened.

It was simply natural for them to be beside one another.

But time is a cruel thing. Their boyish bodies gradually changed into those of adults, and their innocent gazes eventually came to hold emotions they would not show to others.

Just hearing their name called made their hearts race.

Just being smiled at made them helplessly happy.

Even the slightest gesture caught the eye strangely.

And above all...

It became unbearably loathsome to see that person show a friendly face to anyone other than themselves.

What kind of emotion that was... perhaps the two had known for a long time. But they pretended not to know.

Because.

The two would eventually become a pair. Eventually become a married couple. Eventually enter the same house, bear children, and continue the bloodline. That had been spoken of as something all too natural.

That is why they had no way to confirm whether the emotion sprouting in their hearts was "something decided by the family" or "their own desire."

If there was only one thing certain, it was not because the family wished it, nor because the parents decided it. It was not ordered by anyone. It was not taught by anyone. And yet, helplessly...

If it wasn't that person, they didn't want anyone else.

Not because of lineage. Not because of the family name. Not because of the genders of Alpha and Omega.

Simply, as one human being.

They desired another human being.