Chateau Felix is south of Baccarat. For you can enter and complete this sidequest any time during your journey, provided you have a Ship. When you enter the Chateau, Tom won't allow you to pass unless you have what he describes as Kindess to animals (Whatever his standards are). There are answers that are also required for entry.

+ "Take it home and ask your family to let it stay"
+ "Free the tiger from the trap and let it go"
+ "Let the great sabrecat join you on your travels"

Once inside, Felix will give you the Sand Of Serenity to deliver to Baumren who is wandering by a tree; which appears only during the Dawn. Which at that Tom will be waiting with a sabrecat. Four sabrecats points to the location of Baumren, which is eventually obvious. Once you've arrived to the location, there will be a circle of rocks, wait there. At dawn, a tree will appear and Baumren will initiate a short scene. After the scene, check under the tree for a rare, Yggdrasil Leaf. You may also return there at dawn for another leaf. Once you return to the Chateau, you'll recieve the Baumren's Bell.