Keigo Tatewaki, nicknamed "Takki," serves as the Prime Minister's secretary within a special organization connected to Jewel Land's magicians. His duties involve preserving the secret existence of Jewelpets while aiding efforts to retrieve them.

He first appears intervening in a jewelry store robbery to rescue Rinko Kougyoku and Minami. This encounter prompts him to disclose his organizational ties. Recognizing Rinko possesses Ruby's Jewel Charm, he entrusts her with the Jewel Pocketbook. Tatewaki's primary mission is overseeing Rinko's progress in gathering scattered Jewelpets and preventing the evil Jewelpet Diana from acquiring them first.

Tatewaki is initially serious and strictly follows the Prime Minister's orders. However, he displays unpredictability, sometimes making mistakes in his duties or showing visible annoyance at the Jewelpets' antics. Despite these flaws, he consistently supports Rinko and her friends. His skills include martial arts proficiency and thorough research capabilities, though these are often challenged by the Jewelpets' magical unpredictability.

A significant shift occurs when he nearly reveals confidential Jewelpet information, leading him to partner with the Jewelpet Flora. This partnership signifies increased responsibility in his role. His surname "Tatewaki" translates to "sword," reflecting his combat abilities, while his given name "Keigo" combines characters suggesting "open/begin" and "I/me."