Gil's asking for certain aragami materials which are both have the "Teeth" kanji symbol at the end. just withdraw whatever deposited item you have that has the last character as "teeth" kanji until he gives you the ok (teeth symbol= third/last kanji of the bracketed materials).
Remember to free up space when devouring for items.
Btw, for Gilbert's Episode 4 , you are gong to need 夜叉兜片 and 鳥神腱 which come from yaksha/yaksha raja and Shio/fallen Shio respectively. [the "/"s show my uncertainty from which items come from, so just hit both?]
In Gil's episode 5, equip an upgraded Shirogane Blade (you can take it off after finishing conversation with Gil before mission).
For Gil's episode 6, you'll need 堕鳥翼x1、雷砲体x1、氷砲体x1 which respectively can be gained from Fallen Shio, Fallen Zygote(thunder), and Fallen Zygote (Ice).
For Gil's ep7 ,you have to equip the upgraded Shirogane Blade again.
For Gil's ep8, 獣神雷牙x1、女王牙x1、夜叉乱糸x1 are what you are going to need. Defeat Vajra, Prithmi Mata, and Yaksha/Yaksha Raja respectively for the materials.
That's all you need to know for Gil's episodes I think, cyas -cheers. I think I'll just copy this text to the Character Episodes page since I've already typed it.
Sorry, mispelled. "Shiyou" is what I mean. They sound almost the same in Japanese, so I'm used to typing them like that. Curses upon the fool who thought it would be nice to make two similar sounding confusing names.