Shimamura Moritsura served as a bushō and retainer of the Uragami clan of Bizen Province. Moritsura further served as the lord of Takatori Castle in Bizen.
In 1533, prior to becoming an official, Moritsura appears under the name of Shimamura Yasaburō, a young influential figure with authority to directly adjudicate border issues. During the Tenbun era (1532 to 1555), Moritsura served along with Uragami Kunihide and Kakuda 佐家 as a commissioner, jointly signing documents related to diplomatic and adjudicatory matters. Together, they conducted provincial affairs on behalf of their youthful lord. Moritsura was an elder within the Uragami clan, serving as a district governor in Bizen, a role similarly held by Shimamura Hidehisa and Shimamura Kagetsura.
According to non-authenticated military chronicles from the Edo period, Moritsura did not get along well with Ukita Yoshiie, another retainer of the Uragami. In 1534, Moritsura joined with Ukita Kunisada to attack Yoshiie at Toishi Castle. Built in the 1480’s by the Uragami, Toishi Castle was a mountain fortress that served as a strategic base for the clan. Kunisada’s father, Ukita Hisaie, became the castle chamberlain. At the time of the attack, Yoshiie was in retirement, having assigned the role of lord of the castle to his son, Ukita Okiie, in 1524. Okiie had a six-year-old son, Ukita Naoie. Yoshiie killed himself, while Okiie fled with Naoie and was left to wander. Kunisada took Yoshiie’s place as lord of the castle. According to some accounts, Moritsura first became lord of the castle and Kunisada followed as lord thereafter.
After the capture of Toishi Castle, Moritsura exerted his influence within the Uragami clan. Moritsua, along with another senior retainer named Nakayama Katsumasa, was killed between 8/29 of 1559 and the end of 1562. Given that the Uragami siblings reconciled at the end of 1562, Moritsura may have been held responsible for the political changes or was eliminated by Uragami Munekage for being an impediment.