Jetter Mars' personality is that of a spoiled child, similar to that of Uran. He's also said to be very dumb, and will often-times do and say very dumb things, and is ignorant of the world around him. He does, however, mature quite a bit throughout the series, especially when his little brother Melchi is introduced. Dr. Kawashimo created his miraculous artificial intelligence, making him almost human, while Dr. Yamanoue created the robot's body, endowing him with astoundingly powerful weaponry.