Kirari serves as one of the twin star fairies, guarding celestial phenomena in the night sky alongside her counterpart Kirara. Her duty focuses on vigilance over stellar bodies, distinct from her sister's role of actively creating shooting stars.

Sibling strife leads to their fall from the celestial realm to Earth. While Kirara lands near a lake and finds immediate aid from Anpanman, Kirari meets a different fate. She arrives near the castle of Dr. Hiyari, who conducts experiments to boost mental and physical powers. Exposure to these experiments twists Kirari's mind and form. She transforms into a colossal, dark-colored entity, gaining unspecified special abilities and emerging as a mysterious black fairy.

Her transformation coincides with the appearance of the "Devil Star" in the twins' now-vacant starry sky. This entity looms with apocalyptic power, threatening global destruction. Kirari's altered state, likely influenced or exploited by Dr. Hiyari's environment, becomes entangled with this cosmic threat. She acts as a figure under external control rather than an innate villain.

Resolution comes when Anpanman confronts both the Devil Star and Kirari's circumstances. His intervention breaks the hold on Kirari, restoring her original form and mind. Reunited with Kirara, the twins reclaim their place as guardians of the celestial domain, their journey marked by disruption, manipulation, and recovered purpose.