Princesa Domenica is the Colombian Spanish dub name for the Japanese character Princess Karen (Karen-hime) from *Yattodetaman*. In the Italian adaptation *Calendar Men*, she is known as Principessa Domenica. The name "Domenica" means "Sunday" in Italian, aligning with that localization's time-themed naming. An 18-year-old princess from the year 2981, she hails from the Kingdom of Fir. As the direct descendant of protagonists Wataru Toki and Koyomi Himekuri, she is the legitimate heir following her father's death. Her mission is to secure her throne by locating the Cosmopavone (called the Firebird or Jujaku phoenix elsewhere), a mythical entity whose possession legitimizes rule. This sacred creature travels through time and space, disguising itself as significant historical or mythological objects.

To achieve her goal, she journeys back to 1981 with her guard robot Daigoron. There, she recruits her ancestors, Wataru Toki (Beppe Domani in Italian) and Koyomi Himekuri (Tina Ieri). She wields paranormal abilities to detect temporal shifts and Cosmopavone transformations via the Pavonputer. Using these powers, she masterminds missions by guiding Beppe, empowering him to transform into the superhero Yattodetaman. She reveals childhood talismans owned by Beppe and Tina are keys to summoning the powerful future robot Hypergenio King Star.

Throughout the series, she remains in 1981, coordinating the search for the Cosmopavone and countering the antagonistic "Autumn Dynasty," led by Prince Komaro (Prince Sabato) and Princess Mirenjo (Princess Monday). Her role is primarily strategic: leveraging her abilities to sense the Cosmopavone and direct the heroes. Portrayed as honorable and duty-bound, her actions are driven by a solemn commitment to reclaim her throne and preserve her kingdom's legacy.