This is a Spinoff of a Spinoff to the Main series. So naturally I will spoil some stuff.
The story follows Hokaze Junko, a girl from Shokuhou Misaki's group, who is a character from the main universe who's whole existence is considered a spoiler by some fans.
They say stuff like "You have to read NT11 FIRST if you don't you get SPOILED" while that information in itself is a spoiler.
But since NT 11 does not exist in anime or Manga form, just ignore those people. The Manga is great by itself and although there are not many issues out yet, it's quite enjoyable and I
love the depth that was added to a former side-side character.
Junko is a strong female lead that seems to be an airhead, but when shit hits the fan she's pretty good at holding her own.
The plot does not have a conclusion for the first arc yet, but so far the growing mystery makes me wish the chapters would release sooner.
Since the actual pacing is rather slow, you might have to reread the last chapters once a new chapter drops, because you have forgotten what happened so far. But I'm certain, once the first arc is finished, it will be good. I hope this gets an anime adaptation in the future.
Edit: Turns out it was just one Arc. Was stil very good. I recommend it 10/10 would read again.