Usagi Sachiken was a shugenja of the Hare Clan and grand-nephew of the late Master of Earth, Isawa Sachi. In 1171 he was studying at Shiro Tamori when the inaccesible castle was in risk to be sieged by the bulk of the yobanjin Army of Fire during the War of Dark Fire. Sachiken, and another guest, Isawa Nakajima, left the castle. They were tasked to pass to the Imperial Court several of Tamori family's most sacred works, their greatest research and most important formulae. Shinjo Naota and Utaku Anhui, survivor scouts from the Junghar patrols deployed by the Unicorn Clan in the area, escorted them to safety.