Roto (郎党; retainer) or rodo was a family member or a follower of his master's house in the samurai society of medieval Japan. It was also written as 郎等 (roto).
A class of samurai who had come from Johei Tengyo kunkosha (people who distinguishably served in the Johei and Tengyo War) or their descendants were also a Tato-fumyo (cultivator/tax manager), a rice field manager. They worked hard at their training of martial arts while managing rice field, and whenever mobilized for military by kokuga (provincial government offices) they participated in the military activities. Thus, they were acknowledged as local samurai by kokuga and thereby obtained their status as a samurai.
(the kokuga forces system)
In order to maintain a certain level of fighting power, the above mentioned local samurai established the relation of master to servant with their followers who were called roto. Roto could not be declared as having equal status to samurai but had the right to ride a horse like local samurai and the obligation to participate in battles. Some roto originated from lower ranked people or shoju (retainers), and some were peasants who had formed a relation with a local warrior to become a roto.
Like roto, 'ienoko' (followers) followed samurai and participated in battles. The difference between the ienoko and the roto was that the ienoko was a family member or a son of samurai and had a blood tie, while roto was not.
Sometimes a samurai created master to servant relationships among samurai and became another samurai's roto. Around the eleventh century, as leading samurai like MINAMOTO no Yorinobu who should be called toryo (a leader) appeared, many samurai connected master to servant relationships with toryo and become roto for the toryo.