Goth: A Novel of Horror

From Wikipedia:

The Goth novel is actually six short stories about two high school students: a boy who remains unnamed until late in the story, and a girl named Yoru Morino. Both share a similar interest in gruesome murders. While the stories were originally published in a single hardcover edition, they were later published in two bunko volumes. Tokyopop's release follows the original one volume format.

The Stories are:

1 - Goth (暗黒系, Ankokukei, Dark Type)
2 - Wristcut (リストカット事件, Risutokatto Jiken, The Wristcut Incident)
3 - Dog (犬, Inu, Dog)
4 - Twins (記憶, Kioku, Memories)
5 - Grave (土, Tsuchi, Soil)
6 - Voice (声, Koe, Voice)