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