Danganronpa: Trigger Happy Havoc Anniversary Edition

Pretty straightforward achievement - you need to gather 999 Monocoins during your various playthroughs of the game. I'm unsure if it's 999 at once or not, but you might as well just save up until you have 999 to help keep track of the achievement too - there's no need to spend coins until you're nearly done with the game as the items you need to buy offer no in-game advantages.

Getting Monocoins is pretty easy too - there are three main ways to do so:

1. You can receive Monocoins by selecting seemingly irrelevant or random objects in investigation areas. For example, in Makoto's room, if you select the trash can, you'll get one there. If you spend time with Celeste during Free Time and complete her events, you'll unlock an ability called Raise after the third event - this triples the Monocoins you receive from these spots, giving you 3 per spot.

2. Completing class trials will be your main source of Monocoins during your first playthrough. Depending on your performance, you'll be awarded Monocoins - I was averaging about 100-120 per trial with A Ranks, so you might vary slightly. Celeste's Raise ability gives you 10% extra on these amounts too (you don't need to activate this by the way - once you unlock it, it's a passive ability and automatically increases the amounts you receive). With six class trials spread throughout the game, you'll get a hefty chunk of this achievement done just by playing through the game as normal.

3. Completing Warlockuma in School Mode will net you 200 Monocoins on each playthrough you do it. Again, if you're going for all achievements, you'll need to do this at least 3 times anyway, so that's 600 you'll get with no extra effort.

As you can see, you'll pretty much hit 999 Monocoins without having to go out of your way - just save up everything you receive during your first playthrough of the main game and once you've done School Mode twice, you should be on 999. Also note - you can't go above 999, so once you hit it, spend some in the Gallery section to avoid wasting future gains.

If for whatever reason you need more and you've finished everything else, the fastest way to grind them out would probably be to complete the first class trial repeatedly through Chapter Select. You could also do a School Mode playthrough for the guaranteed 200, but this seems much longer and requires more effort. However, there should be no need to grind if you just save up.

Hope this helps clear up a few things!