Ankoku Joshi

The manga is set at a school named the Virgin Mary Girls Academy, where Itsumi Shiraishi, the beautiful daughter of the school's director, recently died. Whether the death was an accident, a suicide, or a murder remains a mystery, known only to the lily that Itsumi clutched in her hand as she died. Rumors begin to circulate that the members of the literature club that Itsumi supervised were responsible for her death. With leadership of the club transferring to Sayuri Sumikawa, the club members continue their practice of reading short stories they wrote to each other. One week, they meet to read stories with theme of "Itsumi Shiraishi's death," with each of the five members intent on using their own story to discover who among them murdered Itsumi.

(Source: Anime News Network)