PSYCHOLOGICAL

From Midnight Scans:Kitou Hijiri, a student, confessed his feelings to a Chemistry teacher named Nakatani Ayano whom he had fallen in love with 8 years ago. Somehow when he was young, he lived beside Ayano and bear feelings for her. Ayano, in turn, could not resist Hijiri's determination and strong feelings towards her. What will be the ending of their taboo love?

From Kotonoha:Seventh grader Hayashi Renei is troubled by a strange dream: Her dead brother-- killed in an automobile accident--comes back to life as Coo. The dream comes again the following night and then every night thereafter. Coo's world is a cruel one--crueler than the real world, even--with its own share of pain, suffering, and sadness. Renei is searching for her house with her brother and others whom she meets in Coo's world so that she can return to reality and the land of the living...

A disturbing manga inspired by an even more disturbing movie of the same name (aka Suicide Club). As you might expect, they both deal with the theme of suicide. However, the plots of the manga and movie are significantly different, so don't wory about spoilers and such. Finally, I'd just like to point out that the manga isn't for the faint of heart, and the movie even more so.