To cook the Jukusen, in principle, only flames (secret fire (imibi)) produced by firestones or maigiri-shiki (style using gimlets (maigiri), ancient tools for making fire) is used.
熟饌の調理には、本来は燧石、舞錐式などで起こした神聖な炎（忌火・いみび）のみを使う。