Full list of all 38 Danganronpa: Trigger Happy Havoc achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Unlocked all gallery items
Earned every other achievement in the game
Collected every possible present
Saw every possible School Mode ending
Collected 999 Monocoins
Filled in every page of Kyoko's Report Card
Filled in every page of every character's Report Card
Filled in every page of Hifumi's Report Card
Cleared School Mode once
Filled in every page of Yasuhiro's Report Card
Filled in every page of Aoi's Report Card
Filled in every page of Toko's Report Card
Filled in every page of Kiyotaka's Report Card
Filled in every page of Mondo's Report Card
Filled in every page of Chihiro's Report Card
Filled in every page of Sayaka's Report Card
Filled in every page of Leon's Report Card
Cleared the 30 SP threshold
Filled in every page of Byakuya's Report Card
Filled in every page of Celeste's Report Card
Cleared the 20 SP threshold
Filled in every page of Junko's Report Card
Finished every chapter
Finished Chapter 5
Destroyed 500 white noise lines across all class trials
Finished Chapter 4
Finished Chapter 3
Filled in every page of Sakura's Report Card
Finished Chapter 2
Destroyed 100 white noise lines across all class trials
Enjoyed the exciting excitement of the MonoMono Machine 100 times
Collected 50 unique presents
Finished Chapter 1
Cleared a class trial without taking any damage
Cleared every class trial without having to retry a single time
Cleared every class trial without using your Concentration skill a single time
Cleared the 10 SP threshold
Finished the Prologue