Here is the full list of all 17 Corpse Party achievements.
Attained the true ending to Chapter 5.
Viewed every ending.
Attained all endings and found every name tag.
Attained the alternate ending to Chapter 5.
Attained the "loop ending" to Chapter 5.
Completed Chapter 4.
Attained all endings in Chapter 4.
Completed Tooth.
Completed She Knows a Key.
Completed Meeting of the Minds.
Completed Chapter 3.
Attained all endings in Chapter 3.
Completed Chapter 2.
Attained all endings in Chapter 2.
Completed A Gentleman's Errand.
Attained all endings in Chapter 1.
Completed Chapter 1.