The 47 Ronin
In the Edo period of Japan, samurai often took an oath of loyalty to their nobleman, which included avenging his master’s death. As the story goes, nobleman Asano Naganori had 47 samurai sworn to him, so when he was forced to commit seppuku (to take his own life) in 1701 following a dispute with another nobleman named Kira Yoshinaka, the samurai’s oath was activated.
The samurai felt the seppuku was unjustified, but they waited two whole years, giving Yoshinaka a false sense of security, before enacting their revenge. Then, one night, the 47 ronin (a term for samurai who lack a master) snuck into Yoshinaka’s home, confronted him, and offered him a chance to commit seppuku. When he didn’t, they removed his head and placed it in front of their master’s tomb. They later surrendered to the authorities, however, and were sentenced to commit seppuku themselves.