A comedic adventure takes place in our solar system, focused on a dispute between the Nohara family and extraterrestrial beings over Shinnosuke's younger sister, Himawari. The initial argument stems from Himawari snacking on Shinnosuke's crème caramel, leading to the sudden appearance of two mysterious men. After signing a questionable agreement with them, the Nohara family is whisked away by UFO to the Planet Himawari. To save both Earth and the Planet Himawari from an impending crisis, Himawari must ascend to the position of princess, as decreed by Sunday Goronesky the Great.