Serge Flora appears as a mysterious photographer wandering Europe's landscapes, presenting himself as an intrepid reporter documenting beautiful locations. His activities involve capturing images and gathering intelligence, crossing paths with the main protagonist during her travels. He frequently aids others by gifting packets of flower seeds symbolizing lessons learned through their experiences, drawing upon the language of flowers—such as offering thistles to signify independence after someone resolves to pursue personal dreams, reinforcing narrative themes of floral symbolism.

His background and motivations remain concealed until later revelations show he is the Crown Prince of the Flower Star, sent to Earth to oversee the search for the legendary Flower of Seven Colors, crucial for the ascension of a new ruler. Despite his royal status, he maintains a humble and supportive presence, often intervening to assist the protagonist and her companions against antagonists.

His relationship with the protagonist evolves from mutual respect into romantic affection. After the Flower of Seven Colors is discovered flourishing in her grandparents' garden—a result of accumulated kindness from those aided during the journey—he proposes marriage, asking her to become Queen of the Flower Star. She declines to care for her aging grandparents on Earth. In response, he abdicates his throne, ceding it to his younger brother, and chooses to remain on Earth to build a life with her, resolving his arc through dedication to their relationship over royal duty.

In supplemental media like the OVA *Hello Cherry Country*, he appears in Japan during a cherry blossom festival, maintaining his supportive role. He continues aiding the protagonist against recurring adversaries threatening natural beauty, extending his protective presence beyond the main series' European setting.