Hail, Mighty Heroes!
After a minor interruption to save the Dragon Clan's coastal areas from unseasonally bad weather --- the tun mi lung (typhoon dragon) threat being negated, and a trip to the outlying area of the Celestial Court -- our heroes once again spend some time researching the Shards of the Bloodwhite Stone -- and turning some of their vast accumulations of treasure into additional powerful enchantments.
Although it took much effort, with shamans, sorcerers, wu jen and shugenja all working at the research with both their magical and intellectual abilities, it has indeed been determined that the Obsidian Caverns is the current resting place of one of the Shards -- indeed, it has been discovered that the Arcane Air shard is supposedly there. However, all attempts to scry or otherwise gain further direct information about the Obsidian Caverns and its denizens seem to be failing. Indirectly, some information has been gained, in the form or "hearsay" type responses from spirits, third- and fourth-hand mentions of bits of conversation, and so on.
The consensus among the spirits is that a variety of Oni (of the bizarre kinds, not the Oni Lords of the mountains kinds) make the Obsidian Caverns their home, though some Oni merely visit there for one reason or another. It is not known who is the current Master of the Caverns -- or indeed if there IS a Master in residence.
What is definitely known is that the Obsidian Caverns are at a center of Chaotic and Evil energies, and serve as a focus in some way for those energies. Evidently the caverns are inimical in some way to creatures which are not Chaotic or Evil -- perhaps even somewhat inimical to any creature which is not both. Though the latter seems somewhat unlikely -- certainly not all Oni are Chaotic, thouggh the vast majority (not counting the Oni Lords) are indeed Evil.
Other things that have been determined using spells and research:
The Obsidian Caverns interferes with magic -- both arcane and divine -- in some fashion. It doesn't make it impossible, just difficuly to use with certainty, and with some sort of backlash when it fails. What that backlash consists of was unable to be determined -- perhaps because in some way it is inconsistent. Though this may present some problems for the spellcasting crowd, it may also hinder the spell-like abilities of many Oni. (Perhaps in that fashion providing a location where Oni are less likely to be using such abilities against each other...and certainly a reason why it seems impossible to scry anyone there, another good reason to make it a hideout for bad guys...)
There was one cryptic comment from one spirit -- "seek the chamber with no entrance to find what no oni owns". No further clarification could be gotten on that.
According to one minor functionary in the Celestial Bureaucracy, the Obsidian Caverns have been declared off-limits to all Subjects (in the Spirit World) of the Celestial Court. This ban does not apply to mortals and other visitors, though they should be warned that contact with the Court may not be possible from inside the Caverns.
The Obsidian Caverns appear to have been formed when a large quantity of volcanic lava burst to the surface and cooled into a massive lump of obsidian with bubbles in it... They were eventually modified to link the bubbles together and made marginally "habitable".
Some spirits claim to have overheard Oni saying things like "the Baths are invigorating at the Caverns, you ought to try them". They think that was in reference to the Obsidian Caverns.
Other spirits claim that the last Master of the Caverns was supposedly a Gaijin Serpent Lord, a great red wyrm with a Heart of an Oni. He hasn't been seen for a while though. And nobody seems to remember his name.
And that is about it, further research both mundane and magical seems to be just going over old ground, so to speak. It has been quite a while (insert actual time spent by the PCs on other activities here) and no other emergencies or adventures have presented themselves -- perhaps it is time to go to the Obsidian Caverns and see for yourselves what is to be seen...
-- Ernie III / DrakaraGM