Zan'e: Sunde wa ikenai heya (2015) online

I is a successful writer of mystery-novels. One day she receives a letter from Kobu, a young student who recently moved into an apartment near her university. At night she hear strange noises and scary voices that got her afraid. She pleads I to help her. As a mystery-writer, I smells the ultimate story and decides to help Kobu. Together they uncover the truth about the people who lived in Kobu's apartment before. And it is a dark story full of anger, hatred, murder and suicide.