Scientists from the University of Tokyo have created a concept called JIZAI ARMS – these are additional robotic arms for studying social interaction of mfuture human cyborgs.
JIZAI ARMS is a small backpack with 6 ports for connecting robotic arms. That is, if a person has both arms, then they will receive as many as 8 upper limbs (two more and it would be the Hindu goddess Durga). But it is possible to use one additional hand. The user should be able to control their hands, but so far they are not able to perform any even slightly difficult work, this is primarily a kind of art project.
According to the authors, the JIZAI ARMS system was created to “enable social interaction between multiple wearers, such as an exchange of arm(s), and explore possible interactions between digital cyborgs in a cyborg society.”