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