I'm Kupo for Kupo Nuts!
Though their exact properties are unknown, moogles seem to be capable of performing great feats of strength when tempted by, or after eating, a Kupo Nut. The player gets a Kupo Nut every time they deliver a letter to a moogle via Mognet provided they do not have one already. Vivi gets the first Kupo Nut via an Active Time Event in Lindblum.
The player can deliver the Kupo Nuts to Moguta in Gizamaluke's Grotto for prizes, usually a Tent or an Ether, but occasionally the player can get something more valuable such as an Add-on. Oddly enough, Moguta, after getting one, has more and more baby moogles running around each time the player returns. Additionally, the player can get an Aloha T-shirt after a certain number of Kupo Nuts delivered.
Non-Final Fantasy AppearancesEdit
Kupo Nuts appear in Kingdom Hearts χ[chi] as a rare item that can be exchanged for Assist Cards. When encountering a Moogle in the wild, the player can either exchange one Unripe Kupo Nut (in infinite supply) for a weaker Assist Card, one Ripe Kupo Nut for a stronger Assist Card, or three Ripe Kupo Nuts for five stronger Assist Cards at once.