'This box seemed to be encrypted with runes. This should be the runic lock that relies on magic runes, and if someone tries to open it without the runic key, the item inside will be destroyed. But I don't think the legendary key is so feeble that it could be destroyed with an advanced unique rank runic lock,' Jacob mused as he observed the box with scrutiny.
If it had been before, he might've been stumped and tried to break this box, but after he deepened his knowledge of the magic runes in the dark city and created the Planet Destroyer, he was very familiar with this kind of runic lock.
He also had Free Sword's entire treasury, so he quickly searched among his treasures and soon found what he was looking for. It was a small pentagon, which perfectly matched the pentagon grove above the box.
Jacob quickly inserted this small pentagon in the grove. When it was perfectly fit, the runes on the box lit up, and with a faint click, the box opened.