Jumbo (ジャンボ) is a discontinued giant robot in the 2003 series. He was created as an engineering marvel for the first annual Robot Expo, but was deactivated not long after. He is over 100 feet tall and holds the world record for the largest robot on Earth, but now sits dormant outside Metro City Marine Park.
Jumbo was created as a showpiece for the Robot Expo, 20 years before the show's current timeline. Visitors to the expo could visit and talk to Jumbo despite his limited AI. He was most popular with small children, who were allowed to climb into his giant hands.
Astro's teacher Ms. Midori, who was 7 years old at the time, was chosen to present Jumbo with flowers and the song "Big Robot Jumbo" on the evening of the Robot Expo. After the expo, Jumbo's power was drained, and he remained sitting in the bay as a monument. His popularity declined with the increase of smaller, more advanced robots.
Jumbo stands at approximately 100 feet tall. He is impervious to bullets and most laser beams. The nearby Chroizier Prison's defense wave - the Guardian Pulse - has no effect on Jumbo because of his limited AI. There is a manual control centre in Jumbo's chest, originally intended as an emergency override or for manual movement. Jumbo has not received proper guarding or maintenance, and as a result, he has accumulated rust.
Jumbo has very limited AI, but can communicate with humans. He is very kind and polite, especially towards small children. When children climbed into his hands, a protective banister would slide up from his hands to guard them. He is also fond of Ms. Midori, and when she was a child, thanked her for her song. This song has remained in his AI as one of his fondest core memories.
Jazz and Blues of Skunk Kusai's criminal group once reactivated Jumbo under ulterior programming, taking advantage of Jumbo's primitive AI and controls. He was used as a tool in destroying Chroizier Prison to break out Skunk. When his human controllers were removed, Jumbo was left to walk automatically straight towards Metro City's shores. Ms. Midori sang "Big Robot Jumbo" to him, which successfully overrided his hack and returned his AI to normal.