Tiara is the younger sister of Kou and Teru Minamoto, and the eldest daughter of the Minamoto clan. She is shown to be a cheerful girl both in off the bonus illustrations and spin-off manga. She calls the Mokkes cute and doesn't even hesitate to rescue a Mokke from a huge, insect-like monster, hence showing that she isn't scared of the supernatural.

Spoiler

Apparently, her spiritual powers far surpass that of Teru's even in her young age, making her the most powerful member of the siblings.