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