Monthly Shōnen Magazine
A prequel series, "Mutsu Enmei-ryū Gaiden: Shura no Toki" also ran in "Monthly Shōnen Magazine", premiering in July 1989 and running until November 2005. Its chapters were published in 15 "tankōbon" volumes by Kodansha. It was adapted into a 26-episode anime series by Media Factory and Studio Comet that aired from April 6, 2004 until September 28, 2004 and is licensed for release in North America by Media Blasters.