Here is the full list of all 25 Shards of Eradine achievements.
Make a chicken use fowl language
Leave Cosmo's home and travel onward to further shores
Visit the market stall in Caronte to sell an item
Set sail to Castareggia
Talk to the local drunks in the pub
When the time is right, make a wish at the well
Choose Kenta to bring on your journey
Choose Nina to bring on your journey
Climb the mountain with Frea to reach Safattia
Help out Adrian with his Eggstraordinary task
Enter the tournament of Safattia and win with style
Find Mika's Banana
Defeat all the flowers protecting the Earth Shard
Calm the Drunks in the winery
Get past all the guards on the castle ground floor
Find Amperia's hidden treasures
Reach the end of Garam's Lab
Reach the Royal Bedroom chambers
Visit a grave in the Dark Town
Reach the Fantasy Zone
Talk to the PotMan
Climb the final stairway
Start a New Game Plus after completing the game
Take a look at the Nymph Gallery
Sell Athos the item he desires