Here is the full list of all 17 Ys I Chronicles+ achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Complete Ys I on Nightmare difficulty.
Master every achievement in Ys I.
Unlock all details for all non-boss bestiary entries.
Complete Ys I Time Attack.
Complete Ys I on any difficulty.
Completely fill the character notebook.
Make Dogi break through three different walls.
Max out your money.
Listen to Reah recite her poem.
Rescue Luta Gemma from monsters in the field.
Receive a free Talwar prior to entering the tower.
"Measure" Feena in the creepiest way possible.
"Measure" Feena.
Level-up Feena.
Confuse and astound the townsfolk.
Drive a hard bargain with Pim.
Receive a free Short Sword.