New interior

My shop's interior has reverted to what it was after I took down those skins. This is definitely not something I want. But I haven't been able to do anything about it yet, as I couldn't find any suitable material.
So I asked for advice from various quarters, and I heard that there is an item good for decorating the shop interior. Apparently, the feathers from monsters called Dark Wings do not provoke the monsters to attack my customers, unlike the skins.
The reason for that is unknown, but perhaps the monsters avoid attacking because those Dark Wings are very powerful monsters. If it's true, then it would be perfect for me. After all, you carry a weapon to deal with emergency situations. So I would like you to get them for me.
Please make your way to the <HFFFA7272>Fallen Hills<HFFFFFFFF> to hunt the <HFFFA7272>Dark Wings<HFFFFFFFF> and obtain <HFFFA7272>10 Black Feathers<HFFFFFFFF> for me. That should be enough to decorate my shop splendidly.

Catch Dark Wings from the Fallen Hills and bring back 10 Dark Wing's Feather.

With this, I don’t think I will need to worry about the shop interior anymore. Thank you for helping.