Battle Royale: Angel's Border is a side-story to Battle Royale. Despite being a manga, it actually takes place in the novel universe, as Sakamochi is the Program Administrator, not Kamon. It covers events happening a few months earlier and during the main story, focusing on a specific subset of the same characters: the Lighthouse group and Shinji Mimura. It is best read after completing at least issue 9 of the Manga or Chapter 64 of the novel. The book has just one issue and two stories by original author Koushun Takami and illustrated by Mioko Ohnishi and Youhei Oguma.