The 4 Sacred Treasures or also known as "The Instruments of God" are the main focus of the story. Currently the Shikyou members are looking for them.
It is said that a long time ago there were four heroes who wielded these four items. Together they would give the user incredible power equal to a God. Many adventurer's focus on somehow claiming these aspiring treasures however very few have ever seen it.
Shiro and Judy are two of the very few who has actually found one of the 4 treasures. During their journey together they found one of the treasures which turned out to be a trumpet. The trumpet alone doesn't do anything including making no noise no matter how much you blow on it. It apparently can only be used when the 4 treasures are together.
It seems that many of the Shikyou are looking for the instrument so that they can cause an event known as the "Feast of God." It is unknown what this will do but it seems that all the Shikyou are expecting it and that the Seven believe it might cause another "Great Shikyou War."
The trumpet Jingi was in possession of Shiro, but was taken by Kurokiri. The second Jingi that was revealed was in Necropolis in possession of Jack.