Born around 1535 to a local lord of Settsu. He rose through service under the Ikeda clan and caught Nobunaga's eye, eventually being entrusted with all of Settsu, with Arioka Castle in present-day Itami as his base. In 1578 he suddenly revolted against Nobunaga—reasons debated, including collusion with Honganji, internal discord, or personal grievances. When Nobunaga sent Kuroda Kanbei to negotiate, Murashige imprisoned him in a dungeon. After over a year of siege, Murashige fled alone to the Mori, abandoning his family and retainers. Arioka fell in 1579 and hundreds were executed. After the Honnoji incident, pardoned by Hideyoshi, he returned to Kyoto and spent his final years as a renowned tea master under the name Dokun, dying at age 51.

Ambitious and decisive, he rose rapidly under Nobunaga. Yet his sudden revolt and abandonment of family and retainers reveal a complex character. In his later years he devoted himself deeply to the tea ceremony and earned renown as a tea master.

Arioka Castle ruins remain a historic site in Itami, Hyogo. As a tea master he took the name Dokun and had connections with Sen no Rikyu. He stands as a uniquely complex figure in Sengoku history, embodying both betrayal and aesthetic refinement.