Go Toba - The Primary Retired Emperor

The primary retired emperor at the time of the joku rebellion was go toba. Go is a prefix meaning latter, so you'll sometimes see his name written as toba the second in older sources. Gotoba would remain on the throne for 15 years before abdicating in favor of his son tsuchi mikato. He would then go on to become the major power at court despite being rather for a man of the imperial court.