He is the second Starzinger / Spaceketeer to join the quest. He is the most intelligent member of the group and is often the one who solves the problems that they meet on their quest, when these problems require logic and not just might.

To the best of my knowledge, he is also a cyborg, although he doesn't possess Cogo / Jesse's abilities.

Evidence of this is given in one episode when they land on a beach to go swimming. Princess Aurora struts around in a pink bikini while Cogo / Jesse and  Darco / Arimos procede to drool profusely.

They then complained that they had to go swimming in their armor because it was attatched to them and they could not remove it, no doubt because they were cyborgs.