A manga called 'Higyaku Hime'. Something about it just deeply disturbed me
http://www.mangago.me/read-manga/ibitsu/
http://www.mangago.me/read-manga/book_club/
http://www.mangago.me/read-manga/toshi_densetsu/
http://www.mangago.me/read-manga/ghost_hunt/
http://www.mangago.me/read-manga/mahou_shoujo_of_the_end/
http://www.mangago.me/read-manga/saiteihen_no_otoko/
http://www.mangago.me/read-manga/zero_kage_miko/
http://www.mangago.me/read-manga/rei_kage_miko/
Shiki is great ^^
I don't think it scariest I've read but have you tried corpse party?
Either higurashi or elfen lied...
Give me the scariest manga you've read! ヾ(❀╹◡╹)ﾉ~