The early Edo ghost-story collection Shūchin-sō records that after the Summer Siege of Osaka, a great strange fire appeared, vanished, and wandered over the paddies at Tanoue in Wakae, Kawachi (there called simply “fire”). Sekien later popularized Battlefield Will-o'-Wisp as a generic name for such lights at battle sites. They were often seen alongside headless warriors searching for their severed heads, though detailed accounts of injury or attack are scarce.