Here is the full list of all 21 Sentimental Death Loop achievements.
Time leaped.
Akane joined.
Suzuka joined.
All three of them came together.
I entered the study.
I entered the Japanese-style room.
Unlocked the password of the room PC.
I unlocked the password for the PC in the study.
I found a hidden room.
Cleared the puzzle in the crafting box.
Returned the breaker.
Found a basement.
caught in a trap.
"Hide" success.
Successful escape.
I listened to the whole story.
All four of them were present.
4 Returned to life.
5 lives returned.