Bookmark of Thanatos

Chouko Mizuno is a high school girl and an aspiring amateur writer. One day, she overheard a story about a serial-killing barista, whose acts were making the news, and her normal daily life suddenly became quite extraordinary.

(Source: ComicWalker, translated)

Note: Commercial serialization finished with 10 chapters in two volumes. Author announced subsequent chapters will be self-published on Pixiv.