As Jinwoo continues his training, he completes a daily quest one day by doing more than the quest requires, and a key that leads to a certain item appears in front of him.
They probably fled the dungeon. 
Happens all the time.
.على الأرجح أنّهما هربا من الدّيماس. يحدث ذلك طوال الوقت
Sie haben nun mal die Flucht ergriffen.
Das kommt vor.
Ils ont dû prendre la fuite.
C’est plutôt courant.
Immagino siano scappati.
Сбежали, наверное?
Не первый раз уже такое.