Blood-Stained Bookmark (血栞塗 Chi Shiori Mitoro) is a short story that is part of an anthology of short stories based on the Thus Spoke Kishibe Rohan series. It was written by Mirei Miyamoto (宮本 深礼 Miyamoto Mirei) and published by Shueisha. Blood-Stained Bookmark was included with the January 2018 issue of Ultra Jump.
It was then compiled in a collection named Rohan Kishibe Does Not Shout with four other stories, which released for sale on June 19, 2018. Blood-Stained Bookmark is on pages 113-156 in the volume.