To begin with, Endou came to the Adventurers’ guild to ask high ranked Adventurers to help him in rescuing Kouki’s party. Surely even if he could not take them to the dungeon depth, they would at least be able to protect the area around the teleportation circle. And though there were also stationed knights, they would not do anything before they reported this to the Kingdom, and their level was so low that at most they could do was protect the teleportation circle on 30th floor. He needed Adventurers with at least “Silver” rank to protect the 70th floor’s teleportation circle.