One notable demon introduced in the series is Onigirimaru, a legendary cursed sword known for having a demon sealed within it. The sword belonged to Ryuma, one of the greatest samurai in Wano Country's history. According to the Wano legends, Onigirimaru contains a powerful oni (a type of Japanese demon) that grants immense cutting power to those who wield it. However, wielding the sword also comes with the risk of being possessed by the demon's malevolent spirit.