Kara no Kyoukai Mirai Fukuin - the Garden of sinners/recalled out summer

Also known as Future Gospel, the "lost 8th chapter" of Kara no Kyoukai that was supposedly written long ago by Nasu, but was never released. It was released as recalled out summer during Comiket 74 for 1,800 yen.

The original Mirai Fukuin was only supposed to be around 30 pages, but evolved into a 192-page book in the final version released during C74. Also, one of the character who appear in the story, Seo Shizune, had an entry in the Rakkyo glossary (bonus material from the collectors edition):

Seo Shizune

A girl in her late-teen. A student of Reien woman academy. Azaka's roommate. Prescience.
A nervous, shy and withdrawn girl. A protagonist of "Mirai Fukuin" that is an extra story included in plotting process(of Kara no Kyokai). Her turn was lost in finished work(KnK), but a charactor with same concept appears in the extra story of Tsukihime.
"Mirai Fukuin" is just a small talk of Mikya and her. That takes place in Ahnenerbe, planed as about 30 pages long idle talk. It's before Mujun Rasen.