Quest name: Goblin Collector Collect 1 ”Crown of Junk"　（ガラクタの王冠） From the Goblin King in the Goblin hideout on floor 82.
If you ever need to find out what quest you have, go to this site: http://fa-wiki.com/sa-online/quest.php
And look for the name of the quest. Right now the quest you are doing is "ゴブリンコレクターの叫び4", you can search for that and any quests after that are below it. Although you won't have someone who can read Japanese with you at all times, you can put the terms into a translator or something and loosely figure out what it is you need to do.