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