Here is the full list of all 51 The Legend of Heroes: Sen no Kiseki I KAI -Thors Military Academy 1204- achievements.
Earned all achievements.
Achieved student rank A0.
Received the Lionheart Medal of Heroism from Principal Vandyck.
Completed all quests, both extra-curricular and during field studies.
Completely filled the monster guide.
Obtained all recipes.
Caught all varieties of fish.
Completed all of the character profiles in the notebook.
Completely filled the book section of the notebook.
Opened every treasure chest in a single playthrough.
Gathered all 28 varieties of master quartz.
Completed the game on nightmare difficulty.
Completed the game on hard or nightmare difficulty.
Acquired over a million mira.
Played for over 100 hours.
Raised a master quartz to level 5.
Acquired the strongest weapon for any character.
Won 100 battles.
Won 500 battles.
Won 1000 battles.
Initiated 300 advantage encounters (including double and triple advantage).
Used 100 S-Breaks in battle.
Canceled enemy arts and crafts 100 times.
Won a battle with a tactical bonus of x2.0 or greater.
Defeated 8 enemies at once.
Raised any two characters to Link Level 5.
Used over 500 follow-up attacks in battle.
Used Rush in battle 100 times.
Used Burst in battle 50 times.
Earned an S-Rank on any chapter.
Forged a strong bond with Alisa.
Forged a strong bond with Elliot.
Forged a strong bond with Laura.
Forged a strong bond with Machias.
Forged a strong bond with Emma.
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 Crow.
Forged a strong bond with Sara.
Forged a strong bond with Towa.
Arrived in Trista for the first day of school.
Completed the prologue.
Completed Chapter 1.
Completed Chapter 2.
Completed Chapter 3.
Completed Chapter 4.
Completed Chapter 5.
Completed Chapter 6.
Completed the final chapter.