20 Seiki Denki Mokuroku is a Japanese light novel written by Hiro Yūki and illustrated by Kazumi Ikeda, with art and backgrounds by Momoka Nagatani. Kyoto Animation published the novel under their KA Esuma Bunko imprint in August 2018. An anime television series adaptation also produced by the studio, titled in English as Sparks of Tomorrow, premiered in July 2026.