As far as I know, none of Akaishi’s works are officially considered horror, but many qualify as mystery or suspense (and some are easily as bloody as recognized horror titles). Ten yori mo Hoshi yori mo ("Than the Heavens, than the Stars") is probably the most popular of these "mysterious romances." It is a good series, especially if you’re familiar with the relevent history and legends. Obviously I like Asterisk even more, although my absolute favorite of the mystery genre is actually the short story Soshite Tenshi wa Hohoenda ("And the Angel Smiled").
All of Akaishi’s works have the characteristics most readers associate with girls’ comics: a softer, less realistic art style and a strong romantic bent. But they also have a delicacy surprising to those readers more familiar with the histrionic soap operas which are all too common in any media intended for girls.
Featured Series: Asterisk
When Ayame moves into town with her sister, she considers it just the latest in a lifetime of such moves. But it is here that she will first encounter the Asterisks, people who are sensitive to the presence of devils. Ayame soon learns that it is not the power of an Asterisk that allows her to see the devils around her, and she uncovers her family’s secret past as well as a prophecy for her own future.
(The title is supposed to be a reference to the hexagram. Early on, one of the characters asserts that it is called "asterisk" in "a foreign language." Along with most mainstream girls’ artists, Akaishi does have an unfortunate tendency to get her background information wrong. But if anyone can prove her right in this case, please let me know!)