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.
Completed the final chapter.
Completely filled the battle section in the notebook.
Won 600 battles.
Opened every treasure chest.
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.
Achieved an academy grade of Prestigious.
Gathered all 28 varieties of master quartz.
Completed Chapter 4.
Achieved instructor rank S.
Collected all radio material and reported it to Munk.
Forged a strong bond with Machias.
Forged a strong bond with Jusis.
Forged a strong bond with Fie.
Forged a strong bond with Alisa.
Forged a strong bond with Millium.
Forged a strong bond with Elliot.
Forged a strong bond with Gaius.
Forged a strong bond with Sara.
Forged a strong bond with Laura.
Forged a strong bond with Emma.
Forged a strong bond with Elise & Alfin.
Forged a strong bond with Altina.
Forged a strong bond with Musse.
Forged a strong bond with Towa.
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 Ash.
Completely filled the recipe section in the notebook.
Raised any two characters to Link Level 5.
Took all landscape photos and reported them to Vivi.
Completely filled the cards section in the notebook.
Initiated 300 advantage encounters (including double and triple advantage).
Completed Chapter 3.
Raised a master quartz to level 7.
Used 100 S-Crafts in battle.
Completed Chapter 2.
Used Burst in battle 50 times.
Inflicted Break over 800 times.
Used over 500 follow-up attacks in battle.
Used Rush in battle 100 times.
Completed Chapter 1.
Earned an S-Rank on any chapter.
Acquired over a million mira.
Used Brave Order in battle over 100 times.
Won 100 battles.
Won a battle with a tactical bonus of x3.0 or greater.
Completed the prologue.
Completed the orienteering exercise.