The official X account for The Ramparts of Ice (Koori no Jyōheki) confirmed that a dedicated fan book for the series is slated for release on January 4. This collection will provide readers with a new epilogue chapter, extending the narrative beyond the events of the series' final installment. Created by Kōcha Agasawa, the story depicts the social dynamics of four high school students, led by the reserved Koyuki Hikawa. The work was initially published as a webtoon on the LINE Manga platform from January 2020 through April 2022. Shueisha later adapted the material into a 14-volume print series, which finished in February 2025. The franchise has also transitioned to television, with a two-season anime adaptation currently available for global streaming on Netflix.