Start the quest by speaking to Lynn. Lynn is upset that the Legendary Ghostmask Armor of Invincibility is part of the Legendary Eight Treasures of the Land while none of her armor is. Lynn believes that her armor is just as good as the legendary one and to prove it she offers to make you a set of armor. Before she can make the armor, Lynn needs a few materials from you: 10 Three Tailed Fox's Fur and 1 Ancient Tree Bark.