Settsu Province
was a retainer of Ikeda Katsumasa, head of the powerful Ikeda clan of Settsu Province. Under Katsumasa, Murashige sided with Oda Nobunaga following Nobunaga's successful campaign to establish power in Kyoto. Murashige became a retainer of Oda Nobunaga and "daimyō" (feudal lord) of Ibaraki Castle in 1573 and gained further notoriety through military exploits across Japan.