Danganronpa 2: Goodbye Despair Anniversary Edition

This one is rather straightforward. Simply collect 999 Monocoins, which is the maximum amount of coins you can hold at any given time.

This achievement is NOT cumulative, meaning you have to have 999 coins all at once. So try to spend as little coins as you can until you reach this just to make it easier for you.

By the end of your initial playthrough, you will probably earn around 600 coins give or take. From here, you have primarily 2 different ways to reach your goal:

The first is that you can go back and replay trials. You can earn coins each time you complete a trial, even if you are replaying it. This is not what I feel is the most efficient way to earn large sums of coins, but it still works great and also can help you earn any of the trial related achievements you may by chance have missed.

The second is what I find to be the absolute best way to earn coins, which is to raise Monokuma pets in Island Mode, which is unlocked after finishing the story. In order to have your pet evolve into Monokuma, you must get the Hope level to 9-10, and the Despair level to 6-9. Once you fully raise a Monokuma pet, you will be given 300 coins, which is the most of any pet. So you can keep raising Monokuma pets repeatedly to maximize coin gains.

NOTE: You should also be able to obtain this achievement by raising each type of pet, which in itself is another achievement. I wrote a guide for that achievement as well which gives a more in-depth dive on how to raise each specific pet.