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