Tokugawa Yoshimune
Tokugawa Yoshimune established the Oniwaban as an elite cadre of originally about 20 handpicked onmitsu, providing him with information about "daimyō" feudal lords and shogunate officials, while also protecting high-ranking officials of the government and acting as security guards in the Edo Castle. They were possibly quartered in the garden of the castle, hence the name.