K1-B0—or "Keebo" as he is known colloquially—is a robot equipped with recording functions and a hyper-advanced artificial intelligence, allowing him to learn and mature like any other teenage human. Raised by his creator, Professor Idabashi, Keebo was allowed to enroll in high school alongside other humans. He was later recognized as an Ultimate due to his robotic nature.

Keebo has a very earnest personality and conducts himself in a proper manner. However, he is very sensitive about the issue of "robophobia"—prejudice toward robots—and will not hesitate to call out any and all instances of anti-robot discrimination.

Because he's a robot, he has a tendency to overlook the subtle nuances of human interaction, and often makes innocent comments that land him in hot water. Kokichi in particular enjoys teasing him over this quirk.