In outline, it's fascinating. Unfortunately, we're almost halfway through before the show does something interesting with its ideas. Ep.6 is indeed very strong, though, and the remaining episodes are worth watching. I was mildly disappointed by the ending, though.
It's based on a mobile phone game. You play fairy tale characters like Cinderella, Snow White, etc. and you're trying to stop Chaos Tellers from destroying people's stories.
In the anime, though, that's pretty twisted. There are lots of Story Zones, each representing a different fairy tale. (Joan of Arc is one of them, but I can forgive the historical handwave because the effect is to allow a brutal downer ending. Joan gets burned to death and it's our heroes' job to ensure that this happens.) What's more, everyone in every Story Zone is born with a book that details their life. No one else can read it. You will follow the script as laid down in your book, even if this means betrayal, murder and/or being eaten by wolves. Furthermore, story roles can be inherited, so there will have been lots of Long John Silvers, Aladdins, etc. and the death of the current one is a routine hiccup, easily rectified.
Oh, and Gilles de Rais is fighting alongside Joan of Arc as her loyal lieutenant. No mention is made of his future child murders, but there he is.
Our heroes' books have blank pages. In a Story Zone, that's regarded as weird and suspicious. They travel between stories together, fighting Chaos Tellers.
That's an incredible premise. You can imagine how people might react to some of their fates. That fuels quite a few disasters. Snow White (ep.6) is a holy shit episode, taking some of the most gruesome versions of the fairy tale and going in some shocking directions. I liked ep.9 too, especially Aladdin's plot role. There's interesting exploration and speculation, but...
1. The Chaos Tellers themselves tend to be boring. They're world-hopping supervillains who turn people into monsters. Time after time, an episode will have set up an intriguing situation and messed-up people... only for it all to get squashed into a big fight when the Chaos Tellers arrive. In fairness, I like their motivation. When we eventually get to talk to them, you'll find that you'd have been cheering for them if it hadn't been for the collateral damage.
2. The expected ending of each episode is unsatisfying. Our heroes save Story Zones by hitting a big reset button. Chaos Tellers are banished, memories get wiped and no one gets a chance to learn anything. (Mind you, the anime's aware that that's uncomfortable.)
3. The open-ended last episode doesn't resolve its questions. This is frustrating, since the original game is dead and there's no chance of the anime getting a second season. The global version was shut down on the day of this anime's ep.1 broadcast. The Japanese version followed suit the following year.
4. The cast are only okay. Reina's stupidity can be annoying, e.g. when falling for very dumb traps in ep.5. (Hang a rope over the edge of a cliff and wait for someone to pull it and die. Well, nearly die. I never knew that Robert Louis Stevenson's Treasure Island had Indiana Jones rolling boulders.) Ex is nice enough, but a predictable pure-hearted anime protagonist. Tao and Shane only became interesting after we'd seen their Momotarou backstory in ep.8.
5. Oh, and characters tend to get tweaked in generic anime directions. Female characters are almost always young and pretty, as indeed is Long John Silver (in a bare-chested male way) and the seven dwarves (here, fairies).
The impression I get is of a series that's obliged to follow the boring pattern of its original games (fight the Chaos Tellers!) but is also aware of the real potential in these ideas. There's a lot of weirdness here. Our blank-book heroes (Ex, Reina, Tao and Shane) can transform into other heroes for battle, even if they happen to be standing in front of the current real version of that hero. Gender can switch. Fates can loop in horrible ways.
This is a Brain's Base show, after all. I like that studio. This is an uneven series, with the good stuff often half-buried under generic anime nonsense, but it's still worth a look.