Jonathan Klondike first surfaces near Clover Tower as Joe Okada, a salesman running a knick-knack booth, later establishing a permanent shop. Blond-haired and wearing a hat, his shopkeeper persona features a distinctive pink apron with heart-shaped pockets. He supplies the protagonist with her transformation device, maintaining a deliberately vague role concerning his knowledge of the magical world.

His true identity is Sir Jonathan Klondike, a royal knight from the Trump Kingdom (Splendorius) and the fiancé of Princess Marie Ange. He journeyed to the human world to find her after the Mercenare's (Jikochu) attack caused her disappearance. His personality mixes approachable warmth with strategic evasiveness, often deflecting questions to encourage independent discovery.

Key actions include protecting the infant fairy Ai from the villain Bel, sustaining injuries in the process. During a critical threat to the Cures, he reveals his knight identity by rescuing them in armor, wielding a sword, disclosing his royal lineage and relationship with Marie Ange. He recounts their shared bond, forged through activities like archery and correspondence, shattered by the kingdom's invasion. Discovering her transportation to Earth via dimensional mirrors prompted his quest.

Following the Trump Kingdom's transition to a republic, he becomes its first president. Later, the villain Kurata impersonates him, nearly inciting an international conflict; the Cures help thwart the plot, restoring his authority. A spiritual reunion occurs with Marie Ange, who had fragmented into two entities; she entrusts him and the Cures with Ai's care before fading away. His residence in the Trump Republic is known as Okada House.