Saimen no Bushi (group of warriors guarding west side of imperial palace) (西面武士)
It is said that it was organized by the Emperor Gotoba in around 1200 to counter the military force organized by the Kamakura bakufu. One of the theories has it that the Saimen no Bushi was organized in preparation to overthrow the bakufu, while another theory holds it that it was created by the Retired Emperor who simply liked military arts, and that it has no relation to the Kamakura bakufu. The name Saimen no Bushi came from the fact that the worriors' station was located at saimen (west side) of In no Gosho (the Retired Emperor's court).
The group's central members were the gokenin (immediate vassals of the shogunate) from Kyoto and the eastern regions, and many powerful gokenin and other outstanding bushi (samurai) from the west Japan belonged to the group. Together with Hokumen no Bushi (a group of warriors guarding north side of imperial palace), which was organized by Emperor Shirakawa to guard the Retired Emperor earlier, Samen no Bushi played a central role in the military affairs of the imperial palace.
In 1221, they participated in the Jokyu War as the army of the Retired Emperor, but were defeated after about one month of the battle. After the Jokyu War, the group was dissolved when the Retired Emperor was sent to exile.