Here is the full list of all 21 CAFE 0 ~The Drowned Mermaid~ achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
You have unlocked all of the achievements.
You have cleared the extra bonus!
You have unlocked all of the CGs.
You have unlocked the True Ending!
They shall get what they deserve!
You remembered what actually happened.
Sui finally cast his magic on you.
You have regained all parts of the Original Heroine!
You have unlocked Shou - Evil Ending!
You have unlocked Shou - Good Ending!
You have unlocked Tooru - Evil Ending!
You have unlocked Tooru - Good Ending!
You have regained all parts of the Good Heroine!
You have regained all parts of the Evil Heroine!
You got your head back!
You got your chest back!
You have unlocked the Bad Ending.
You got your stomach back!
You got your legs back!
You got your arms back!
You have cleared the prologue!