Fukushima Masanori, or as he was first known, Ichimatsu, was born in Owari Province, the son of Fukushima Masanobu. He is believed to have been the cousin of Toyotomi Hideyoshi. He first engaged in battle at the assault on Miki Castle in Harima Province, and following the battle of Yamazaki, he was granted a 500 koku stipend. At the battle of Shizugatake in 1583 (Tenshō 11), Masanori had the honor of taking the first head, namely that of the enemy general Ogasato Ieyoshi, receiving a 5000 koku increase in his stipend for this distinction (the other six "Spears" each received 3000 Koku).