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