Through promises

Hina is Haruhi's cousin on Haruhi's mom side, she has long dark hair and looks vaguely like Haruhi. She goes to Ouran in search of her cousin and what she finds is... interesting to say the least. Hina is pretty normal, like Haruhi, and she is very smart, just like Haruhi.

The only difference (other than appearance) is that Hina is a year older. She is in Kyoya's and Tamaki's class and has everyone in the host club drawn to her because of her unique personality.