how to get Yin-Yang?

[dynastystar]

I was looking at a walkthrough: https://www.gamefaqs.com/pc/979867-the-legend-of-heroes-trails-in-the-sky-sc/faqs/72569?page=1
I'm going through the Limestone Cave and the walkthrough lists "Yin-Yang" as an item. Each item on has its location corresponded to a number, but Yin-Yang doesn't have a number. It just says "--" and I click the hotlink to Yin-Yang and it doesn't say anything in the "Acquisition" section. Before the hotlink it says "requires fire transfer", I am using a file transfer(not a 100% BP file though) but it doesn't say where the item is if I am using a file transfer.

[Hagen2900]

You just need to complete the quest. There is also the requirement of having done a certain side quest in FC.