It was originally an 'Akama suzuri,' a top-quality inkstone made specially in Shimonoseki City, but was possessed by a vengeful spirit of an Ise-Heishi warrior who had been defeated at the Battle of Dannoura.
硯の最高級品である下関市名産の赤間硯に、かつて下関での壇ノ浦の戦いで滅びた伊勢平氏の怨霊が宿ったもの。