Did you think there were only Dark Memory stories? Well, surprise!
Releasing around halfway into the life of the game, Recollections of Dusk were stories that are the mirror to the Dark Memory stories; they acted similarly, gave similar types of stories, and provided a unique costume with a similar convention to that of the other tales. The outfits and weapons parallel the Dark Memories, and they were massively important pieces of content as well. Unfortunately, only characters from the first arc got these. There are some ideas that some of the writers had and thought of for the second arc cast, but for preservation's sake, this will focus on what the game had.
These provided a different take on the endgame grind. You had doors to enter, quests with waves of enemies, and four difficulty options to go through. Each door had elements associated with them and a specific character mandatory in your loadout and restrictions and limitations to who can be used and when, locking you based off what costume you used prior. It made for a much more engaging and different experience than Dark Memories which had so much more of a luck-based grind comparatively, or just throwing yourself at Zenith opportunities.
And to make matters more complicated, you had Burdens that needed mitigation based off specific weapons and loadouts and debuffs. You had a lot to juggle, which is what made it a nice change of pace from the norm!
There's a lot more details on the mechanics of it. User Rondelle made a great guide on nierrein.guide about it which is a solid place to learn more of the inner workings if you're curious, but other than that... let's move onwards.
And don't worry if you were concerned. You're not going to watch all 12 of these back to back. They're spread apart. Think of them as prologues of what's to come.
Let's proceed.