Kojiro operates alongside Musashi and Nyarth as part of Team Rocket. His physical appearance features slightly shorter hair than his main series depiction, and his standard Team Rocket uniform includes minor modifications: shorter sleeves on his top paired with a long-sleeved black undershirt. This design remains consistent throughout the narrative.

During Fula City's Wind Festival, Kojiro and his team disguise themselves as Lum Berry juice vendors to facilitate theft attempts. One such attempt successfully secures a bottle of Effect Spore from a laboratory. However, their escape leads to the accidental loss and cracking of this bottle within the nearby forest, directly triggering the release of dangerous spores that later threaten both city and forest environments.

As the spore crisis intensifies and a forest fire erupts, Kojiro and his teammates shift focus. They relinquish their cart of Lum Berries to the timid researcher Toren. These berries prove essential for Toren to create a concentrated antidote capable of countering the Effect Spore threat, aiding the collective resolution effort.

Kojiro's personality reflects his established traits. He demonstrates teamwork within his small group, participating in both the initial theft and the later assistance. His actions, particularly the accidental triggering of the spore release, drive the film's central conflict. His subsequent involvement in providing materials for the antidote indicates a degree of responsiveness to the unfolding disaster, consistent with his role in the comedic yet troublesome trio.