Shin Geum-Gyu gritted his teeth as he thought, ‘Where on earth did she disappear to…?’

It had already been four days since his twin sister disappeared into thin air. While his team was crossing the forest, a group of monsters had ambushed them. Under the guidance of his team leader, Kim Hyeong-Jun, the team had successfully gotten the monsters under control to an extent. The problem came afterward, because Shin Eun-Seo had disappeared while they were killing monsters.

At first, Geum-Gyu assumed that she had hidden from the monsters or fallen behind the group as she chased after the escaping monsters; after a while, however, he became nervous, thinking that perhaps a monster he failed to notice had kidnapped his sister.

However, no matter how much he scoured the area with his teammates and how many monster hives they raided, Geum-Gyu could not find Eun-Seo. If he had found her corpse, he would have been sad, but he could have at least given up. Nevertheless, he had been unable to find a single trace of her, as if she had evaporated into thin air. Geum-Gyu even asked the instructors, who had said they would protect the trainees in secret, what had happened, but the answer he received was that they had not seen what happened because of the hectic situation, leaving him incredibly frustrated.

Every day from then on was torture for Geum-Gyu. Sometimes he felt so suffocated that he was unable to breathe, leading him to run into the forest alone and scream at the top of his lungs. However, he could not calm down.

Although he had always teased his sister for her immaturity and nagged her about wasting her time and...