Here is the full list of all 51 The Legend of Heroes: Sen no Kiseki II KAI -The Erebonian Civil War- achievements.
Completed the game on hard or nightmare difficulty.
Completed the Epilogue.
Completed all 39 quests.
Completed all of the character profiles in the notebook.
Completely filled the book section of the notebook (excluding books only available in NG+).
Completed the Divertissement.
Completed the Finale.
Used Overdrive in battle 100 times.
Received the Grand Cordon of the Order of the Phoenix Wings from Emperor Eugent III.
Won 600 battles.
Gathered all 31 varieties of master quartz.
Caught all 24 varieties of fish.
Achieved student rank A0.
Acquired the strongest weapon for any character.
Forged a strong bond with Emma.
Forged a strong bond with Towa.
Forged a strong bond with Alisa.
Raised any two characters to Link Level 7.
Obtained all 22 recipes.
Completed Act 2.
Raised a master quartz to level 5.
Used 100 S-Breaks in battle.
Used Rush in battle 100 times.
Initiated 300 advantage encounters (including double and triple advantage).
Used Burst in battle 50 times.
Used over 500 follow-up attacks in battle.
Completed the Intermission.
Completed Act 1.
Defeated 8 enemies at once.
Earned an S rank during part of any chapter.
Won a battle with a tactical bonus of x3.0 or greater.
Won 100 battles.
Completed the Prologue.
Woke up in the Eisengard Range.
Earned all trophies.
Completely filled the monster guide (excluding EX sections).
Opened every chest between the Prologue and the Finale.
Completed the game on nightmare difficulty.
Acquired over a million mira.
Canceled enemy arts and crafts 100 times.
Slayed Isra-Zamiel in Glacia Shrine.
Read the decoded Black Records and had an encounter you'll never forget.
Forged a strong bond with Elliot.
Forged a strong bond with Laura.
Forged a strong bond with Machias.
Forged a strong bond with Jusis.
Forged a strong bond with Fie.
Forged a strong bond with Gaius.
Forged a strong bond with Millium.
Forged a strong bond with Sara.
Forged a strong bond with Alfin.