Born in 1541 in Owari Province (present-day Ichinomiya, Aichi). His given name was Nagatomi (永福), commonly known as Sukeemon. He served Maeda Toshiie and became a senior retainer of the Kaga domain. His finest hour came at the Battle of Suemori Castle in 1584, when Sassa Narimasa attacked with an army of 15,000. As castle commander with only about 300 defenders, Okumura held the main keep even after the second bailey fell, buying time until Toshiie's relief force arrived. This feat earned him renown as the 'most loyal retainer of the Maeda clan.' After Toshiie's death, he continued to serve the Maeda house as head of the Kaga Eight Houses (senior retainer families). He died in 1624 at the age of 84. He is widely known through the manga 'Hana no Keiji,' where he appears as Keiji's rival and friend.

A warrior of unwavering loyalty and indomitable fighting spirit. Possessed the courage to never retreat even when vastly outnumbered, and maintained absolute loyalty to the Maeda house. Also skilled in administration, laying the foundations of domain governance.

His defense of Suemori Castle is remembered as the battle that saved the Maeda clan's future. As the founder of the Okumura house—foremost of the Kaga Eight Houses—he laid the groundwork for the domain's administrative structure. His depiction in 'Hana no Keiji' has made him popular even today.