Chushin-gura "忠臣蔵" is one of the famous play-writes  in Japan which was made by a real incident happened in  in Edo(now Tokyo) on Dec. 14 , 1702. The 47 faithful retainers of their Load Asano carried out the revenge against another load Kira who was a responsible for their Lord Asano's death. The cause of the incident One year before the incident, the Load Asano was humiliated by Kira who was in charge of a big party with the Emperor. Load Asano was made fun of the party's preparation  frequently and accumulated his anger. One day in the Edo castle, the load Asano attacked Kira with his short sword at last. Fortunately, Kira's injury was not fatal. The load Asano was ordered Seppku (suicide by killing oneself by self-disembowelment). Since then, the country of Load Asano was dissolved and the retainers lost their load. The plan of revenge Ooishi was the leader of 47 samurais. The plan to revenge was performed secretly. Most 47 samurais were in Edo disguised them as various citizens like noodle shop owner or carpenter paying attention to the leakage of the plan. The accomplishment of the plan The plan was accomplished at night on Dec. 14 , 1702 in heavy snow. The 47 samurais attached Kira's house and got his head. The 47 samurai went their load's cemetery and reported the revenge showing Kira's head. After that most of them are  ordered to do  Seppuku by the central government called Bakufu.
忠臣蔵2 seppuku
These pics are from the internet.