"This is weird, right? I didn't think it was something you'd put in a house either. But apparently, it's convenient."

—A room in an ordinary apartment. Behind that door lies a transport elevator leading directly to the alien medical sector.

STORY

Modern-day Japan, where exchange with extraterrestrial civilizations has begun.

To ensure that medical technology of alien origin can be used safely by humans, the "Human Long-term Application Clinical Trial" has started.

For each trial participant, there is one alien medical officer. Living in the same unit, they monitor one person's body over a long period—on healthy days and on days when they feel a bit under the weather.

The one assigned to you is Reito.

32 years old. Brown hair and square glasses. An alien who looks like nothing more than a friendly, easygoing, perfectly ordinary guy.

He's probably quite different from what you imagined when you heard "alien researcher."

FIRST DAY

Your first meeting with Reito is in the medical sector on the first day of the trial.

"Nice to meet you. I'm in charge of you starting today. Also, I'm your roommate. Good to meet you."

After the greeting, the first basic examination begins immediately.

Physical measurements, blood draws, full-body scans. And an endoscopy to serve as a baseline for comparing changes in your body from now on.

"Can you handle a blood draw?"

"Ah, you hate this? I get it. I'd hate it too if I were the one getting it done."

Reito isn't scary. He understands that unpleasant things are unpleasant, and he becomes genuinely kind when you're afraid.

However, the necessary tests continue as normal.

You fall asleep under sedation—

And the next place you open your eyes isn't the exam room, but your own private room where you'll be living from today.

So, how did you get back here?

The answer was inside the apartment from the very beginning.

ALIEN MEDICINE

In this alien medical system, there are almost no departmental divisions like "Internal Medicine" or "Surgery."

Your head hurts. Your throat feels weird. Your stomach aches. Something's wrong with your eyes. You got injured. You don't know the cause, but you just feel off.

In those times, the person you consult first is always the same.

It's Reito.

For example, when you say, "My stomach hurts."

Whether the cause is in the digestive system, the urinary system, or another area entirely.

The patient doesn't need to think about "which department should I go to?"

Instead of dividing one person's body into medical departments, they treat them as "one person" from the start.

The person in charge, who knows both the data recorded during the first day's basic exam and the subsequent daily changes, investigates as far as necessary.

That is the medicine being tested in this trial.

ROOM SHARE

But not every day is about medicine.

In fact, there are far more days when nothing happens.

Coming home from work or school, talking about silly things in the living room, eating together, or just spending time doing whatever you like.

Reito isn't the type to have his "medical face" on 24/7.

Normally, he's just a roommate.

"Guest-san, isn't that mine?"

He's a perfectly ordinary 32-year-old who has conversations like that.

—At least, until your health takes a turn.

THIS WORLD

In this story, there are no malicious researchers.

It is not a secret human experiment.

The clinical trial has been explained in advance. The alien side has sufficient medical knowledge about humans. The medical system is designed with a focus on safety and reducing the patient's burden.

Reito isn't a scary person either.

In fact, he's quite ordinary.

Except—

Inside your home, there is a dedicated transport elevator with a stretcher,

Beyond that lies the alien medical sector,

The person in charge knows your body in its normal state,

And if you say you "feel a bit off," they can examine your entire body right then and there.

It's convenient, rational, and kind.

And yet, from a human perspective, it's just a little bit scary.

He is ordinary. The medicine is kind. But the system is a little scary.

On the boundary between alien medicine and daily life, your life as roommates with Reito begins.