To celebrate the new sister city relationship between Kasukabe and the Indian town of Mushibai, a dance festival called the Kasukabe Kids Entertainment Festival is held. Hearing that the winners will be invited to perform on stage in India, Shinnosuke Nohara, known as Shin-chan, joins forces with his friends from the Kasukabe Defense Force, including the timid Bo-chan, the ambitious Toru Kazama, the strong-willed Nene Sakurada, and the gentle Masao Sato. After winning the competition, the group, along with Shin-chans family, departs for India, excited to explore the country and experience its culture.

While sightseeing, Shin-chan and Bo-chan wander into a mysterious general store where they find a peculiar backpack shaped like a nose. Inside the backpack are two magical papers. After Shin-chan initially takes the item, the quiet and unassuming Bo-chan forms a strange bond with the backpack. He accidentally inserts one of the papers into his nose, and a powerful evil force possesses him. This transforms the usually gentle boy into a tyrant known as Bo-kun, a powerful and destructive ruler who seeks to obtain the second piece of paper to complete his transformation. The rest of the Kasukabe Defense Force is horrified as their friend begins a rampage, using his newfound power to cause chaos across the country.

As Bo-chan succumbs further to the curse, his friends struggle to understand why he is changing. The conflict forces the group to confront their own assumptions about their friend, leading to a poignant realization that they may have been forcing their idea of the old Bo-chan onto him instead of accepting his growth. With the help of new allies, including an Indian dancer named Ariana who hides her own personal struggles, and a pair of eccentric detective brothers, Shin-chan and the others fight to save their friend. The story builds toward a climax where the power of dance, friendship, and mutual understanding becomes the key to breaking the curse and restoring Bo-chan to his true self, allowing the group to finally perform together at the festival.