The Tale of the 47 samurai (Chu-shin-gura)

The Sengakuji temple is the gravesite of the famous "47 samurai", a group of warriors who avenged their master's death. Long story short in 1701 Feudal Lord of Ako, Asano Takuminokami got involved in a duel with another lord, Kira Kozukenosuke. The duel took place in Edo castle, a place where drawing one's sword was strictly forbidden. Both of the lords should have been punished for their offense however only Asano was ordered to commit seppuku (suicide). Lord Asano's estate was confiscated and family line deposed and disgraced. The retainers of Asano were outraged and after unsuccessfully petitioning for reinstatement of the estate, went into hiding for two years. At that point 47 of the retainers attacked the estate of Lord Kozukenosuke and exacted their revenge. They reported their deed to the head shogun who appreciated their loyalty and honor and therefore restored their Lord's estate. However the shogun couldn't have this kind of thing happening all the time so he ordered the 47 samurai to commit seppuku, which they did February 4th, 1703.