Here is the full list of all 49 Atelier Ryza: Ever Darkness the Secret Hideout achievements.
Laid eyes on the Underworld.
Installed the Gathering Synthesizer at the secret hideout.
Learned about the history of Ryza and the others.
Installed a Power Reactor at the secret hideout.
Defeated the dragon at the old castle.
Created the Fishing Rod.
Created the Bug Net.
Found one treasure chest.
Created the Hammer.
Wrote a record of one exploration.
Built a secret hideout for everyone.
Witnessed the rise of a strange beast.
Attended a tea party with Ryza and Klaudia.
Created the Reaper's Scythe.
Created the Woodcutter's Axe.
Synthesized for the first time.
Visited the mainland for the first time.
Earned all trophies.
Spent the night camping in the Underworld.
Helped Empel regain his former strength.
Visited the Holy Tower of Pynnor and learn the truth.
Entered the Kurken Bunker.
Created the Crimson Stone and saved Kurken Island.
Saw everyone move on to chase their dreams.
Created the Bomb Rod.
Found and installed all Power Reactors.
Installed the Multiplicauldron at the secret hideout.
Saved the goat you met on your travels.
Helped create Rasen Pudding.
Completed requests to get Peter to interview you.
Got Ryza's battle level to 50.
Became a Braver.
Activated everyone's Fatal Drive.
Got Ryza's alchemy level to 99.
Obtained all recipes.
Created an item with Item Level 99.
Obtained the Revelation Book.
Wrote a record of every exploration.
Found all treasure chests.
Created a bottle with Gathering Synthesizer Level 51.
Defeated the Shining Puni.
Defeated the Savage Assassin.
Defeated the Mirage Master.
Defeated the Eternal Sculpture.
Defeated the Noble Paladin.
Defeated the King of Storms.
Defeated all 5 Great Elements.
Defeated the Queen of Darkness.
Defeated the Queen of Shadows.