Note: A duology of prequel light novels published in May-July 2020. They are set in the world of the 2020 anime TV series 戦翼のシグルドリーヴァ (Warlords of Sigrdrifa). Not to be confused with 戦翼のシグルドリーヴァ Sakura, the other duology of prequel light novels set in the same universe, written by the same author and published in October-December 2020.