Here is the full list of all 39 Death end re;Quest 2 achievements.
Viewed most of the sub-events with your classmates.
Entered Glitch Mode for the first time.
Used a Flash Drive skill for the first time.
Cleared Chapter 1.
Activated Knock Blow for the first time.
Entered Camp for the first time.
Activated Knockback for the first time and sent an enemy back.
Completed all story endings and explored all paths.
Viewed most of the main story.
Viewed the EX Ending.
Defeated the final boss.
Defeated Ao Oni in the Pain Area.
Used Glitch Mode a great many times.
Used Glitch Mode a handful of times.
Viewed the True Ending.
Viewed the Fallen Ending.
Viewed many story events.
Viewed all of the Death Ends.
Defeated 1000 enemies.
Cleared Chapter 10.
Cleared Chapter 9.
Cleared Chapter 8.
Cleared Chapter 7.
Cleared Chapter 6.
Cleared Chapter 5.
Cleared Chapter 4.
Cleared Chapter 3.
Cleared Chapter 2.
Learned 15 of Mai's skills.
Learned 15 of Rottie's skills.
Learned 15 of Liliana's skills.
Learned 15 of Shina's skills.
Learned 15 of Lily's skills.
Learned 15 of Al's skills.
Learned 15 of Clea's skills.
Learned 15 of Lucil's skills.
Learned 15 of Celica's skills.
Played the Ao Oni mini-game.
Activated Super Knockback for the first time and sent the enemy flying.