F i r s t  A p p e a r a n c e

Proto Dome

After Crono with the help from his best friend, Lucca, escapes the prison in Guardia Castle, they run away with Marle to take the closest time gate, which takes them to the Future (2300 A.D.). After learning about the destruction of Lavos and locating their next time gate to get them back home, the trio enters the Proto Dome to be welcome by two battles against robots and their sewage rats. After beating the welcome mats, the trio finds a pile of metallic trash, which Lucca learns is actually a humanoid robot. Since she is the brain of the trio, she repairs him, and the four of them introduce themselves to each other. Unsatisfied with Robo's serial number name (R-66Y), Marle renames him 'Robo'.

Factory  Ruins

After renaming Robo, Marle learns that the door leading to their time gate is locked. Robo tells them that the only way to unlock the door is by activating it using the power from the Factory Ruins. Since the power to activate the door is temporary, one person in the foursome will have to stay behind as the others go to the Factory Ruins. After entering the factory's power storage area, Robo turns on the power to unlock the Proto Dome's door while accidently activating the factory's security system as well.

    As the security system is running, the group tries to escape to the exit until six blue humanoid robots catch them. Robo, feeling secure about the situation, introduces the six blue robots to the group as his robots friends. The six blue robots, however, disapprove his behavior of befriending humans and consider him a 'defective robot', so they beat him mercilessly. After beating the blue robots for beating Robo, the remaining two in the trio bring Robo back to the Proto Dome, so Lucca can repair him. During repairing him, Lucca ask Robo what he wants to do after he is repaired, and he decides that he wants to join Crono and his group on their adventure. Therefore, Robo joins the party as the fifth member of the group.