If you wanna be picky, theres two secret Aeons in the Calm Lands area.

Yojimbo is in the cave at the bottom of the vally. Then theres The Magus Sisters in the temple which you can gain access to when you have a Chocobo.

Yojimbo is fairly easy to obtain as long as you have enough money. But The Magus Sister are abit harder to get hold of.

Check www.gamefaqs.com. There'll be plenty of guides to tell you exactly how to obtain them.