Muramasa

[1] In spite of their original reputation as fine blades favored by the shōgun Tokugawa Ieyasu and his vassals, the katana swords made by Muramasa gradually became a symbol of the anti-Tokugawa movement.

[4] Both sides contain beautiful engravings of Kurikara (Fudō Myō-ō's mythological sword empowered by a burning dragon).

[4] It is also silver-damascened with characters Nabeshin (鍋信), which suggests that the sword was once in possession of Nabeshima Katsushige (1580–1657), the first daimyō lord of Saga Domain.

[9] Another theory states that Muramasa I was a student of Heianjō Nagayoshi, a prominent Kyoto swordsmith known for spears and engravings.

[5] Matsudaira Kiyoyasu, a grandfather of Ieyasu, was mistakenly killed by his own vassal Abe Masatoyo with a Muramasa.

[11] Ieyasu's father Matsudaira Hirotada was also stabbed with a Muramasa by Iwamatsu Hachiya, who lost his mind by excessive drinking.

[11] When Ieyasu's first son Matsudaira Nobuyasu was forced to commit suicide (seppuku), his beheader (kaishakunin) Amagata Michitsuna used a Muramasa.

[5] Honda Tadakatsu, one of the Four Greatest Generals under Ieyasu, wielded Tonbogiri, a legendary spear forged by Fujiwara Masazane, who studied under the Muramasa school.

"[5] Even Tokugawa Jikki [ja] (1849), the official history book published from the shogunate, cites Kashiwazaki Monogatari (柏崎物語, 1787), which tells a legend that Ieyasu regarded Muramasa as cursed items and banned them from his family,[12] although it is clearly a fabricated story considering the heirloom of the Owari-Tokugawa family.

Oscar Ratti and Adele Westbrook said that Muramasa "was a most skillful smith but a violent and ill-balanced mind verging on madness, that was supposed to have passed into his blades.

"[13] It has also been told that once drawn, a Muramasa blade has to draw blood before it can be returned to its scabbard, even to the point of forcing its wielder to wound himself or commit suicide.