Tondekeman is a sentient time machine resembling a stainless steel kettle, wearing sunglasses and capable of human speech in the Kansai dialect. Created by Dr. Leonard, later revealed as Leonardo da Vinci, it projects a dimensional hole from its mouth for time travel; this portal closes after ten minutes.

Destination input occurs via manual dialing of its ear-like components or verbal commands. Imprecise instructions often lead Tondekeman to autonomously select the time and location. Its programming designates the current holder as "master," enforcing strict obedience and causing frequent shifts in allegiance with ownership changes.

Accidentally activated by protagonists Hayato and Yumi in Dr. Leonard's lab, Tondekeman transported them to 9th-century Baghdad and became separated. The recurring antagonist Abdullah then acquired it, exploiting its capabilities to repeatedly kidnap Princess Shalala and escape across historical periods.

Tondekeman demonstrates advanced computational abilities, including human-like conversation and decryption. Its personality blends pragmatic servility with self-preservation instincts, readily switching masters for convenience. A significant malfunction in the fifteenth episode required repair by Thomas Edison.

As the central narrative mechanism, Tondekeman drives the protagonists' quest to retrieve it from Abdullah, enabling encounters with diverse historical and literary figures. Its function concludes upon the protagonists' successful recovery, facilitating their return to their original timeline.