Kokujyuseki

Kokujyuseki, also called Black Pearl, is a precious jewel whose supply has been monopolized by the Oak Family since the Raggs War. Its sale has further increased the Oak Family's wealth.

At Wakaba's funeral, each guest is given a kokujyuseki as a gift in return for a funeral offering.

When Teito Klein first touches the jewel, he suddenly feels a strange disgust and drops it carelessly. Katsuragi picks it up, and remarks that the history behind the kokujyuseki is probably a whirlpool of grudge and vanity, and that the cost the Oak Family and other people have paid for this jewel is unknown.

In manga chapter 77, it is shown that back in heaven when Verloren heard Eve said that feelings cannot be materialized, he materialized the negative feelings (e.g. vanity, jealousy) of human beings and showed them to Eve. They are the kokujyuseki.

Trivia

 * Marshal Wakaba Oak had the duty of disposing of the jewels of the Raggs Royalty after the war. The jewels cannot be burnt like literature books, so he employed a Warsfeil to deal with them. The Warsfeil used black magic to envelop the jewels, and they are the kokujyuseki sold by the Oak Family. Later, the Warsfeil started to auction kokujyuseki statues. Lance said the statues looked so lively and he became suspicious. He discovered that that Warsfeil turned living human beings into kokujyuseki. This caused him to lose his life, as the Warsfeil turned him into a kokujyuseki statue in order to cover his secret. This statue was in Shuri Oak's house until Lance was devoured by Verloren, whereupon it vanished into thin air. (manga chapter 77)
 * The crown of King Weldeschtein Krom Raggs, covered by black magic and in the form of a kokujyuseki crown now, is in Shuri Oak's house at present. (manga chapter 77)