Touki (冬器[1], Winter Blades) are weapons that are used to tame Youjyuu and also have the ability to slay immortals due to spells cast on them.
Because of the nature of the blades, the production and distribution of touki is managed by a kingdom's Ministry of Winter, the ministry charged with the economic affairs of the country. The blades are called to as "touki" (winter blades) in reference to the Ministry of Winter. In order the obtain touki, an weapon dealer must have authorization from the government.