Unless you buy a Kit, items you purchase will always go to the regular inventory first, whether they are NP or NC. From there you will be able to choose whether you want to add the item to your Bookshelf or trade it.
If you purchase a Kit from the NC Mall, however, the Kit will automatically be added to your Bookshelf Inventory. This means that all the items in the Kit will go to your Bookshelf inventory, and the Kit itself will disappear. If you wish to trade individual items in the Kit, you must remove them individually from the Bookshelf Inventory. They will not return to a Kit, and will instead show up as single items in your inventory.
If you think an item is missing, please check to make sure you’re viewing the correct inventory (NP or NC) before sending in a ticket.