The Thirty-One Ronin were a group of former Crab made ronin who were led by Oishi. Oishi had once been Hiruma Oishi, but became a ronin following the death of his master Hiruma Asano. A year to the day after Asano's death, Oishi led his ronin in an attack against the man they blamed for Asano's death, Bayushi Kira. Disguised as firemen, they broke into Kira's estate and killed Kira's men. Oishi killed Kira himself, and presented the man's head to the tomb of his master. Oishi and the ronin were allowed to commit seppuku after surrendering to the Emperor's men. The actions of the Thirty-One Ronin were celebrated by the Hiruma every year on the day of Kira's death.