Buddy (フレンドさん) was a service robot who accompanied Acetylene Lamp when he was shipwrecked. Buddy was programmed to protect humans, and would provide Lamp with food and companionship.
As an older model of robot, Buddy had limited AI. He attempted to learn from Lamp and other humans he had known, at one point trying to tell Lamp a joke. He would send SOS messages through a homemade device, and would bring Lamp fresh fish and fruit on a daily basis. Buddy also maintained a shelter out of the sun for Lamp. Buddy also provided moral support and encouragement that a rescue would come soon.
Lamp and Buddy became friends, with Lamp so interested in Buddy's ability to emote like a human that Lamp swore it would make a scientific breakthrough if they could get off the island. For Lamp's birthday, Buddy decided to obtain ripe papaya from the top of the island. A volcano unexpectedly erupted at the top of the island's peak, stranding Buddy there. Lamp was rescued just in time by a search crew, but Buddy was left on the island and assumed for dead. This left Lamp with a lot of anguish and regret.
Unbeknownst to Lamp, Buddy is now living in Metro City, with a young archaeologist who found him on the island. Buddy remembers having a human friend who called him Buddy, but can no longer remember Lamp's name or who he was.