Nagayoshi was known to have such a bad temper and to be particularly ruthless in battle that he came to be known as the "Devil".
Nagayoshi was gifted with Kaneyama Castle after his father died in battle. While he was under the service of the Oda clan, he was directly under the service of Nobunaga’s eldest son, Oda Nobutada, who fought alongside Nagashima in 1574.
In 1584, Nagayoshi's efforts for Toyotomi Hideyoshi during the difficult Battle of Komaki and Nagakute ultimately took his life. During the battle he rode in front of his lines and waved a war fan frantically.[3] He stood out conspicuously wearing a white jinbaori and was subsequently shot in the head by Tokugawaashigaru firing a matchlock rifle.[3][4] His younger brother Mori Tadamasa became the next clan head.