Demon: Qing-Long
Head to the new area, Kuchinawa Cave, and start roaming around until you find the Beast of Bixia Qing Long. Once you see him, bring his health down to critical levels, but make sure to leave him alive as the in-game clock reaches 03:00 or 15:00, then kill the dragon at exactly one of those times. This condition is so you can spawn the real Qing Long, which, upon killing his mirage, will tell you (as a system/area-wide message) "You've got nothing, human!! With a single blast of my icy breath... I can freeze both your mind and body!!" If you get this message, you're on the right track, for the real one spawned somewhere.
After this, you will have to hunt wherever the real one spawned. Once have found and defeated his chance, There will be a chance that the item Spring Thunder's Rumbling will be on his corpse, which you need to take to the guard at the very start of the dungeon. Talk to him and choose to show him the Thunder's Rumbling, and he'll ask you a series of questions. Here are the answers:
* Damage caused by the Great Destruction
* Their destabilized leylines
* Spring Thunder's Rumbling
Answering correctly will make the Gaian monk take the Spring Thunder's Rumbling and trade it for the Qing Long/Sei Ryuu/Shen Long Plugin: Azure Dragon of the East.