20 Seiki Denki Mokuroku is a Japanese novel written by Hiro Yuki and illustrated by Kazumi Ikeda, with art and backgrounds by Momoka Nagatani. The novel won an honorable mention in the full-length novel category at the 8th Kyoto Animation Awards in 2017, and was the only series to win an award that year. Kyoto Animation published the novel under their KA Esuma Bunko imprint on August 10, 2018 ( ISBN 978-4-907064-88-4). On July 27, 2018, KA Esuma Bunko's Twitter account announced that an anime adaptation of the novels would be produced, and would be animated by Kyoto Animation.