Ghost Hunt, Karakurizoushi Ayatsuri Sakon Recommendations
Why did the deaths occur? Both Anime are arc based and have a Gothic art style to them. The characters are unique as well, and the music is also similar in some regards.
If supernatural mysteries are your thing, here are two series with a lot in common on that line. Great characters and great stories bring both pseudo detectives stories to life with an array of the supernatural that makes them both work. :)
Shoujos about cute guys who solve eerie mysteries.