Question: The Lords of the Akō Domain in Harima Province associated with the story of what 18th-century historical event in Japan in which a band of "rōnin" (leaderless samurai) avenged the death of their master?
Context: Kasuya Takenori (糟屋 武則 , 1562–1607) was a Japanese samurai of the Azuchi-Momoyama Period, in the service of the Toyotomi clan.  He was the second son of Kasuya Tadayasu, a retainer of the Bessho clan of Harima Province.  He held the title of Naizen no Kami (内膳正).  Following the Chūgoku campaign, Takenori became a page of Toyotomi Hideyoshi due to the recommendation of Kuroda Kanbei.  Takenori achieved notoriety due to his distinguished combat at the Battle of Shizugatake, where he was known as one of the Seven Spears of Shizugatake, and for this distinction he received a stipend of 3,000 "koku" from Hideyoshi.  Also served in the Korean campaign, and subsequently was granted Kakogawa Castle in Harima Province. The Asano clan (淺野氏 , Asano-shi ) was a Japanese samurai clan that claimed descent from the Minamoto clan.  The Main Lineage ("sōke", 宗家) were Lords (daimyō) of the Hiroshima Domain in Aki Province and another famous branch family were Lords of the Akō Domain in Harima Province associated with the story of the Forty-seven rōnin.  Their inherited character is "長".  The family came to prominence when the sister of Asano Nagamasa married Toyotomi Hideyoshi. Banshū-Akō Station (播州赤穂駅 , Banshū-Akō-eki ) is a railway station on the Akō Line of JR West, located in Ako, Hyōgo Prefecture, Japan.  The prefix "Banshū", indicating the station's location in the old Harima province, was given to distinguish the station from Akaho Station (赤穂駅 , Akaho-eki ) on the Iida Line in Nagano Prefecture (now Komagane Station), which used the same kanji characters as Akō. The revenge of the forty-seven "rōnin" (四十七士 , Yon-jū-shichi-shi , forty-seven samurai) , also known as the Akō incident (赤穂事件 , Akō jiken ) or "Akō vendetta", is an 18th-century historical event in Japan in which a band of "rōnin" (leaderless samurai) avenged the death of their master.  The incident has since become legendary. Harima (播磨町 , Harima-chō ) is a town located in Kako District, Hyōgo Prefecture, Japan.  The town shares its name with Harima Province, one of the old provinces of Japan.  Harima was known as Ae village until April 1962.  The name "Harima" is derived from a large area in southwestern Hyōgo Prefecture, commonly referred to as "the country of Harima," or Banshū area. The Akō Domain (赤穂藩 , Akō Han ) was a domain in feudal Japan.  It was located in Harima Province and coincided with the present-day cities of Akō and Aioi and the town of Kamigōri in Hyōgo Prefecture.  The domain had its headquarters at Akō Castle. Nagai Naohiro (永井 直敬 , 1664 – July 18, 1711) was a Japanese daimyo of the Edo period, who ruled the Akō Domain following its confiscation from Asano Naganori.  Naohiro was the eldest son of Nagai Naotsune, and assumed family headship after his father's death.  Upon the confiscation of the Nasu clan's territory in Shimotsuke Province, Naohiro was transferred there from his previous holdings in Kawachi, and thus became the lord of the Karasuyama Domain.  Naohiro was appointed to the offices of jisha-bugyō and sōshaban in 1694, and in the fall of 1701, after the execution of Asano Naganori, he received a 3000 koku increase in stipend, becoming the new lord of Akō, with a territory of 33,000 koku.  However, because of the time-consuming nature of his work as jisha-bugyō, the domain's affairs were run by his retainers.  Naohiro subsequently became a wakadoshiyori in 1704.  He was moved to Iiyama in 1706, and Iwatsuki in 1711; Naohiro died soon after the move, in the summer of 1711.  His son Naohira succeeded to the family headship. Takebayashi Takashige (Japanese: 武林 隆重 , 1672 – March 20, 1703) was a Samurai in the early Edo era of Japan.  He was involved in the revenge of the Forty-seven Ronin incident (also known as the Akō incident) as one of the ronin.  Takashige was originally a subordinate of the Daimyo Asano Naganori, master of Akō Domain. Ōishi Yoshio (大石 良雄 , April 24, 1659 – March 20, 1703) was the chamberlain (karō) of the Akō Domain in Harima Province (now Hyōgo Prefecture), Japan (1679 - 1701).  He is known as the leader of the Forty-seven Ronin in their 1702 vendetta and thus the hero of the "Chūshingura".  He is often referred to by his title, Ōishi Kuranosuke (大石内蔵助 ) . Akamatsu Norifusa (赤松 則房 ) (1559 – August 18, 1598) was a Japanese samurai of the Sengoku and Azuchi-Momoyama periods. Norifusa served as the "shugo" of Harima Province, but was defeated during Toyotomi Hideyoshi's Chugoku Offensive.  He surrendered, becoming Hideyoshi's vassal; in subsequent years he was granted landholdings scattered around Okishio (in Harima Province) and Sumakichi (in Awa Province).  Under Hideyoshi's command, he saw action at the Battle of Shizugatake and the Shikoku Offensive.
Answer: forty-seven "rōnin"