Japan was a country in turmoil at the beginning of the 18th century. It was a time of pageantry and corruption in the Shogun's court in Edo (now Tokyo) and of riotous gaiety in the pleasure quarters of ancient Kyoto, shuttered away from the world of social restraint. The arts flourished; the popular theater was born. Because the merchant class was rising in power, it was also the beginning of the end of privilege for the professional warriors, or samurai, who felt their loss keenly, especially since they held the business of money-making in contempt.
In the midst of such bewildering change, eruptions of violence were not unknown. They came most often in the form of rice riots by the farmers who were taxed beyond endurance by the Shogun, the military ruler of all Japan. That they did not occur more often among the samurai was a tribute to the thoroughness of their training and their remarkable self-discipline.
But even a samurai could be pushed too far. Especially a rash young lord forced into contact with the effete and degenerate ways of the court.
It happened in 1701 in Edo. In a moment of anger and frustration, Lord Asano of Ako lashed out at a corrupt court official and set in motion a chain of events that terminated in one of the bloodiest vedettas in Japan's feudal history. These events shocked the country and brought the Shogun himself to a legal and moral impasse. When it was over, Japan had a new set of heroes—the forty-seven ronin, or ex-samurai, of Ako.
—From the preface by John Allyn