The Murasame is obtained under the normal or hard difficulty setting. Select to work for either the Aoto gang or the Magistrates' office. Make sure that whichever you choose, you are completely loyal to the selected job broker. If you choose Aoto, do not work any other broker during the entire game. The same goes if you choose the magistrates; work only for them. One very important factor is that you must not fail a single job from either man you selected. If you chose to work with the Magistrates' office and you have done sufficient jobs, he will give you a job where he will ask you to kill the Aoto Gang job broker. This man wields the Murasame. Kill the job broker and collect his sword. This is the simpler way. Your other option is to work for the Aoto Gang instead and kill the Magistrate job broker when the job arises. After you do this, during the next nighttime period, approach the edge of town. A samurai will be there with a name above him reading "Killer". Talk to him and you will fight him. After his death, he will admit who sent him. Confront the Aoto gang broker as soon as this happens (as in the same time period), and choose the option to kill him. After you are victorious, you will have his sword, the Murasame.