Board Thread:General Discussion/@comment-5551986-20181227102057/@comment-29325824-20190106183936

Well, here is an ongoing and up to date summary of the novel: on the Bleach subreddit.

The novel, overseen by Kubo, is an epilogue story that greatly delves into the history of Soul Society, especially something called "the original sin".

Also, Yyp, the story is deeper and more complicated than you give it credit for. Granted, making the Valley of Screams and Muramasa canon (in a way) was not really necessary, but it does a lot of decent worldbuilding that Kubo never got around to.

"On Hikone - 1st do we need another hybrid of all races? and 2nd, how can you be a hybrid of both Hollow and Arrancar?"

Hikone was artifically created to replace Yhwach with a controllable Soul King; he/she was stated to be a very unstable/catatonic being until Tokinada managed to fuse Gremmy's remains with Hikone.

"I don't get why the fullbringers were a secret or so important. Maybe my imagination is just not good enough but I see no reason why all that would be worthwhile. "

It's strongly implied that all Fullbringers are born with a piece of the SK in them, which is where their unusual matter manipulation comes from. So an understandable need for secrecy.

It also confirms that Gremmy is a part of the Soul King and indeed the strongest Sternritter. Also, Baraggan was one of the oldest Vasto Lorde, the real history of Tosen's friend's murder, history of Xcution & nature of Fullbring, Shinji's Bankai, an extra power of Katen Kyokotsu, etc.