Two-dimensional Doomsday Countdown

January 4, 2019; January 10; January 11 — Age 55

All preparations were complete. Yuji finished readying the civil aviation aircraft at Haneda Airport within three days — refueling, confirming fuel levels, cleaning the runway, and conducting system self-inspections.

The passenger aircraft's test flight on [-] was successful. The weather was calm, with no malfunctions. Yuji was able to fly the aircraft back to the Eastern Union successfully.

At that moment, Yuji stood silently beside the armed U.S. helicopter departing from Yokosuka Naval Base.

"Five minutes left…"

Two days had passed since his first contact with Kasumigaoka Utaha. Since their last call on [-], she hadn't reached out to him even once.

Yuji initially thought there might be an issue with the communication network — maybe the signal was blocked, preventing calls and emails. But he confirmed that she had simply chosen not to contact him.

During that time, he also hadn't reached out to her. He waited, hoping she would take the initiative while he completed the final preparations.

Unfortunately, no message ever came.

Yuji looked off into the distance. Haneda Airport was quiet, filled with planes, yet the girl was nowhere in sight.

"One more minute…"

Yuji lit up his phone screen again, checked the time, and imagined Kasumigaoka Utaha would not be calling.

Now it came down to his choice.

Do nothing — take off and fly out of Japan — or make one last attempt to contact her before deciding what to do next.

"Is this your answer? If so… so be it."

Yuji thought for a moment but decided not to reach out to Kasumigaoka Utaha.

He was probably a little angry.

Even though there was no immediate threat to life in this new world, she still clung to her pride and reserve, despite the two of them being the only people left. If he reached out first, she'd have to understand what that meant — what message that behavior conveyed.

Yuji believed it would be better to leave things be for now, to let her face reality on her own.

She needed to clearly recognize the situation, or their shared future would be difficult.

When she understood, he'd come for her.

In any case, once back in the Eastern Union, he would begin flight training with aircraft.

It wasn't just about learning to fly for over [-] kilometers at a time.

As long as the risks were well-managed and his skills continued improving, it was doable.

As for aircraft-related issues, he could only rely on the knowledge provided by the current "system" and his own post-apocalyptic self-study to improve his capabilities.

"But why does it have to be you as the assistant?"

Seeing a familiar face from his past life made Yuji happy, naturally — but because it was Kasumigaoka Utaha, he also felt guilty for dragging her into this "lonely doomsday."

Sure, someone had to be chosen as his assistant… but if he could help it, he didn't want it to be an old acquaintance.

He knew he wouldn't be able to face her entirely calmly or rationally.

Moreover, knowing her personality, he feared the very thing he didn't want to happen would indeed happen.

One year from now, the assistant would lose all memories of this "Lonely Doomsday" world. To her, this place wasn't reality — it was more like a dream she'd forget upon waking.

"I hope things go better this time."

Yuji was truly looking forward to that — that the next year would unfold the way he envisioned.

Finally, the time arrived.

But no girl showed up at the airport. And his phone remained silent.

"It's time… goodbye…"

Yuji whispered to himself and then boarded the aircraft, entering the cockpit.

The controls and instruments were exposed — but to Yuji, they were familiar.

He wasn't a stranger to the cockpit.

He followed the usual procedures and began operating.

Boom…

The engine rumbled to life from residual heat, and the passenger aircraft shook slightly.

Five minutes later, everything was ready.

The phone sat off to the side, still silent. No messages. No calls.

Yuji shook his head, finally letting go.

Waiting any longer would be pointless. If someone refuses to make the first move, then it's time to go. He hoped Kasumigaoka Utaha could manage living alone here for a while.

In any case, her life wouldn't be in danger — just some hardship with no power or water.

As for food and drinking water, there was more than enough in Tokyo to support one person.

"Goodbye…"

Yuji's voice trailed off as he began the final sequence with both hands.

But in that moment… he felt it.

Even with his seatbelt on, Yuji felt a strong jolt in the cockpit.

The scene through the windshield shook violently, the ground trembled, and loud cracking sounds echoed from all directions.

"An earthquake…"

A building in the distance tilted and collapsed, and fractures opened up beneath the aircraft.

It was definitely an earthquake — and a powerful one.

Yuji's heart skipped a beat.

He shut off the engine immediately, canceled all takeoff operations, unfastened his seatbelt, grabbed his phone, and ran out.

The earthquake continued. The ground shook. The plane on the runway tilted and began sliding.

Without concern for his own safety, Yuji ran straight toward the armed helicopter that had just landed.

In less than three minutes, it took off.

"Don't die!"

The call wouldn't connect. Each "beep" made Yuji's heart sink.

He never wanted her to die.

His decision to leave had always been based on the premise of her safety.

Now that a quake had struck — how could he leave without confirming she was okay?

Yuji could no longer maintain his calm, detached appearance.

But why… why now of all times?

A trace of suspicion crept into Yuji's mind.

Was it truly a coincidence that the earthquake didn't occur earlier or later — but right when he was about to leave Japan?

Yuji also remembered that in April 2019, no major earthquakes had occurred in Japan during the first half of the year — especially not one of this intensity.

There were still significant differences between the two worlds.

His future actions should not be based [-]% on the assumptions of his original world.

...