Big Incisor is a material dropped by Lying Hablerie. It can be sold for Yukiko's Castle 1F¥
Part of Lying Hablerie. The owner of Daidara may be able to use it...
You need to get 5 of these, and sell them to Daidara, in order to get the Hard Boots required by the Man in front of Yomenaido's Book Store. Quest Nº 22 of the Fox (Hermit Arcana).