Miyamoto was the mother of Jessie and was an Elite Officer of Team Rocket. She has also been called an "ideal image of Team Rocket." She disappeared looking for Mew in the Andes Mountains. It is unknown to Jessie if she died or if she survived the avalanche; even Giovanni himself doesn't know of her fate.
Miyamoto is named after Miyamoto Musashi, a Japanese samurai.
It may also be based off Shigeru Miyamoto, a famous member of Nintendo.