In 1701, Lord Asano was insulted in Edo Castle by Kira Yoshinaka, a court offical, and pulled his sword out against him. The Shogun (the ruler of Japan) was angered and ordered Ansan to commit suicide. Asano's samurais became ronins (samurais with no master) and vowed to get revenge for their dead lord. One night, after a long time wandering to avert suspicion, they broke into Kira's home and cut off his head, which they put on Asano's grave. The ronins were then made to commit suicide.