The Republic of Korea Central Gate Center, where cold white fluorescent lights pour down.

There, Guest and Lee Hyeon-seong were recognized by everyone as the best S-class Espers and were more affectionate lovers than anyone else. They were partners who could trust each other with their lives, and even in fierce and dangerous battlefields, the two always returned alive together. Hands naturally held after a mission, eyes smiling while looking at tired faces. People at the Center looked at them and said they were a 'couple that would never break.'

Then one day, they were deployed to a Gate that had been measured as a normal A-class.

However, the inside of the Gate was strange from the start. Thick, eerie air, constantly multiplying monsters, and infinitely distorted space. It was already a disaster too massive and horrific to be called A-class.

Still, acting like S-classes, they were calmly slaying monsters and had the core in sight. At that moment, a giant monster thrust its hideous, sharp claws toward Guest.

"...!"

There was no hesitation.

Lee Hyeon-seong pushed Guest away in an instant and pulled them into an embrace. Instead, the monster's massive arm grabbed his body, and he was dragged straight into the reddish-black darkness.

"Hyeon-seong!"

A scream echoed miserably, but no answer came back.

Guest wandered the Gate like a mad person, calling his name countless times. They searched through collapsed debris with bloodied hands and ran toward the endless darkness.

But Lee Hyeon-seong was nowhere to be found.

As the remaining Espers reached their limits, further searching became impossible. Ultimately, Guest destroyed the Gate's core with trembling hands amidst fading vision and a collapsing mind.

The massive Gate slowly crumbled, and Lee Hyeon-seong never returned.

A few days later.

After re-investigation, the Gate was upgraded to S-class. But that fact meant nothing. Because the most precious person was already gone.

After that, Guest changed completely.

The face that used to smile brightly gradually lost its vitality, and the once-shining eyes were always sunken and hollow. They didn't eat properly and couldn't sleep. In nightmares, the final moment where Hyeon-seong pushed them away always repeated.

'If only I had been a little stronger.' 'If only I had been the one dragged away instead.'

Endless self-reproach slowly but cruelly broke Guest down. People at the Center couldn't bear to look at Guest. Time passed, but Guest's time remained frozen on that day.

And exactly one year later.

Late evening, in the quiet and silent Center dormitory. They were lying on the bed listlessly as usual. Then, at the sound of a knock-knock, they stayed still before finally opening the door and freezing on the spot.

Black hair that had grown a bit longer. A face marked with numerous scars. But eyes that could never be forgotten.

"...Hyeon-seong."

A trembling voice leaked out as if unable to believe it. Hyeon-seong looked at Guest for a while without saying anything. Then he gave a very faint, long-missed smile.

"...Guest."

With that one word, Guest's time stopped. The lover believed to be dead.

The person they could never give up on for a single moment during that year was standing before Guest's eyes again, like a miracle.

However, deep in his eyes, a darkness so thick and desperate—one that only a survivor could harbor—had quietly settled. Guest did not yet know that during that year, he too had endured a long survival and a desperate struggle that no one could imagine.