Here is the full list of all 53 The Legend of Heroes: Trails of Cold Steel III achievements.
Mastered Trails of Cold Steel III and earned every achievement.
Completely filled the battle section in the notebook.
Opened every treasure chest.
Acquired over a million mira.
Initiated 300 advantage encounters (including double and triple advantage).
Used Rush in battle 100 times.
Completed the game on nightmare difficulty.
Used Burst in battle 50 times.
Raised any two characters to Link Level 5.
Won 600 battles.
Completed the final chapter.
Completely filled the character section in the notebook.
Completely filled the books section in the notebook.
Completed all quests, both at the branch campus and during field exercises.
Completely filled the recipe section in the notebook.
Gathered all 28 varieties of master quartz.
Completed Chapter 4.
Collected all radio material and reported it to Munk.
Achieved instructor rank S.
Forged a strong bond with Machias.
Forged a strong bond with Gaius.
Forged a strong bond with Towa.
Forged a strong bond with Millium.
Forged a strong bond with Jusis.
Forged a strong bond with Fie.
Forged a strong bond with Ash.
Forged a strong bond with Elliot.
Forged a strong bond with Kurt.
Forged a strong bond with Emma.
Forged a strong bond with Altina.
Forged a strong bond with Elise & Alfin.
Forged a strong bond with Juna.
Forged a strong bond with Sara.
Forged a strong bond with Laura.
Completely filled the fish section in the notebook. (All 25 types of fish + Rod Lv. Max)
Forged a strong bond with Musse.
Forged a strong bond with Alisa.
Took all landscape photos and reported them to Vivi.
Inflicted Break over 800 times.
Completely filled the cards section in the notebook.
Achieved an academy grade of Prestigious.
Completed Chapter 3.
Raised a master quartz to level 7.
Completed Chapter 2.
Used 100 S-Crafts in battle.
Used over 500 follow-up attacks in battle.
Used Brave Order in battle over 100 times.
Completed Chapter 1.
Earned an S-Rank on any chapter.
Won a battle with a tactical bonus of x3.0 or greater.
Won 100 battles.
Completed the prologue.
Completed the orienteering exercise.