Mewtan acts as a small companion to the central protagonist, typically perched on his shoulder. This creature specializes in detecting danger targeting Jun Yagami, capable of hearing her screams across great distances and swiftly warning the protagonist of approaching threats.

Mewtan hails from another planet, having departed its homeworld before the series events, establishing an extraterrestrial origin distinct from Kirakira's native tribes. The character shares its name and core premise—a small alien entity—with another from a separate Tatsunoko Production series, though this link remains external to the series' own narrative.