Without going in too deep, you probably know what you're into if you're checking this guide.
In order to complete Danganronpa 2, you will need to get every achievement, including "Monomi Won't Miss These, Right?".
So how do you earn it? It could've been something simple like "Beat every stage on Hard difficulty", but no, they went the extra mile and made the requirement for it be "Acquire every single equipable item on the mode"

This wouldn't be too bad, if it weren't for the terrible RNG that this mode has, not to mention some items literally require you to play the lower difficulties, which is kinda dumb because i did my initial playthrought completely in hard, but turns out you can get everything by playing only on Easy and Normal.
This guide is about a trick i found when i was almost done with all the items, but helped me get the remaining ones extremely quickly. Judging by the overall percentage of players that have earned this achievement, which at the moment of making this guide is 1.7% of players (just 0.1% more than the 100% achievement), i would assume almost no one knows about this. Maybe if they knew they'd be more likely to actually try and earn the achievement.

First up, you need certain tools in order to achieve this more easily.
I recommend you play through the full mode yourself once, this will result in you upgrading your equipement as you play, you can do it on Normal or Hard, if you want the challenge you can do it on Hard but if it gets too frustrating just lower it, the only difference is that enemies deal more damage and have more HP, sometimes WAY MORE than they probably should, I personally played it on Hard first because i like challenges but some of the stages are really terrible. Also the final stage literally throws every boss of the mode in the same stage, but at least the final boss literally doesn't do anything, you can usually KO him super easily and quickly.

Anyway, just by playing you will have probably like a bit more or less half of the items that you can find in the mode, it depends on your RNG.
The first important step is to get a specific item that will make item drops more frequent, you need to find the Old Man’s Grass Skirt, which is an equipable item for your diaper slot.
Having this makes everything way easier.
If you weren't lucky enough to find it, you should probably start grinding, im pretty sure that i managed to find it on the first Stage in Normal for the first time.

Remember when i said the RNG of this mode was really terrible? Well i meant it quite literally, there's guides that say in which levels a certain item can be found, but not all of them are consistent with each other, and in fact you can pretty much find some items that are catalogued as "appears in easy early areas" in the last level of the game, its a total mess to be honest.

This guide has some of the item locations, most turned out to be "true" in my experience but as i said, its pure RNG and you can find them by chance somewhere else, however the ones that clearly only appear on lower or higher difficulties will indeed only be found on them, but as i stated before, dont bother with Hard for the grind.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=677496337

Alright, here's what you've been waiting for.
First equip your most powerful wand and ribbon, tho you probably should've done so already. I actually managed to find the "Hope" items on my normal playthorught, ironically the last items on the list (and also the most potent ones) sometimes appear more often than some of the others close to them.
The trick for grinding the items specially applies to some of the harder ones to earn, im talking about the ones listed as appears in Stage 5 or Special in Normal, which also happen to be the items at the end of each list, however this can be applied to some of the lower ones, just go on Easy for those, they're more likely to appear there.
So, what you're gonna do is, with the diaper mentioned above equipped, go into the Special Stage on Normal, kill the first batch of enemies that make up Wave 1, shouldn't take longer than 10 seconds, if the items they drop is not what you need, or if you don't get any at all.... JUST RESET THE STAGE UNTIL YOU GET AN ITEM YOU'RE MISSING.
After you get said item.... RESET ONCE AGAIN TO KEEP SEEKING THE OTHER ITEMS.
Sounds crazy? Perhaps, but turns out you just need to pick up an item for it to be added to your inventory, "normally" ending the level isn't required.
This means you don't need to win or lose the stage, you can reset or even leave, as soon as you grab the item and you see the text prompt that says what it was, you're free to go back to the level select, or reset the current one without losing your progress.
I found myself doing this on the Special stage because not only the placement of the enemies helps so much to KO them quickly, but also i usually would get 1 or 2 item boxes from that batch of enemies before reseting. Not to mention it being the last stage helps you get those rare items.

USE THE "Old Man’s Grass Skirt" AND KEEP RESETING WAVE 1 OF THE FINAL LEVEL UNTIL THE FIRST BATCH OF ENEMIES GIVES YOU EVERYTHING YOU NEED.



Yeah its that simple i discovered it when i accidentally reset the level after finding one of my final... 3 items i think, the moment you grab it, it's registered on your inventory.
I was really frustrated to discover it when i was almost done, but as a result the other 2 items i needed popped up in less than 3 minutes by doing this lol.

So... why did i do this and why should you?
Well before you had to have some mental condition if you wanted to endure doing this thing, but hey! if you use this trick you will probably take an hour at most, and not 5 like i did.
As for me... well i didn't see this ANYWHERE while i was looking for info on how to get the achievement, and also by the time i wanted to abort writing this guide i was halfway done so i decided to go all out an finish.
I hope you liked it, i might add some images to this soon maybe, I hope i could help someone out with this so they dont have to suffer what i did.
Good luck!
Here's the pic of me finally getting the thing and earning the final achievement (yes to no surprise i left this to be the very last thing i did on the game)