The most I've heard about it is from Yima herself, and... D. I spoke with him when he came to visit Highstorm to check on Gen and Atsumu.

[The man had included Rin in that group but she's eager to gloss over and not think about that. Instead she pours tea for the two of them, and delicately places a porcelain teacup and saucer before link. A small pitcher of cream and a matching bowl of sugar cubes are also available.]

There is reason to believe that Oblivion is coming for this place next, and that they've already started interfering with Oracles. Or at least that's what I suspect after encountering the monster under Yima's mansion, hearing about the shared dream shard-bearers who died during the Harbinger Oracle had, and what D had told me.