Here is the full list of all 36 Valkyria Chronicles 4 achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Obtained all achievements.
Obtained all decorations.
Obtained all infantry weapons.
Obtained all tank parts.
Obtained A ranks on all missions.
Triggered a Last Stand 15 times.
Watched all event scenes.
All of your classes were upgraded to max level.
Recruited all squad members.
Gave ship orders 15 times.
Obtained all ship parts.
Kept your promise with Riley Miller.
Learned all orders.
One of your classes was promoted to Paragon status.
Completed Chapter 18, and ended Belgar's dark ambitions.
Defeated 1000 enemy units.
Completed Chapter 17, and witnessed the end of the war.
Completed Chapter 15, and defeated both Walz and Crymaria.
Gave orders 15 times.
Gave direct commands 15 times.
Rescued 10 allies in critical condition.
Defeated 15 enemy aces.
Obtained A ranks on 20 missions.
Completed Chapter 11, and made it past the Sea Fortress.
Earned 1,000,000 DCT cumulatively.
Developed the Hafen into a heavy tank.
Completed Chapter 7, and rendezvoused with the Centurion.
One of your classes was promoted to Elite status.
Completed a squad story for the first time.
Completed 10 missions without anyone in critical condition.
Completed Chapter 4, and won the battle of Siegval.
One of your squadmates was promoted to Corporal.
Learned an order at the Mess Hall for the first time.
Defeated an enemy ace for the first time.
Used R&D Facility for the first time.
Obtained an A rank on a mission for the first time.