Sakuya

Sakuya behaves very much like a modern teenager and is fashion conscious. She would love for her brother to see her as woman and not just a sister.
In both anime, Sakuya claims that she and the brother are connected by the "red string of fate" and expresses the desire that she might somehow marry her brother. She is quick to agree it would be impossible when in his presence. In the anime, Sakuya is arguably the most emotionally vulnerable of all the sisters where the brother is concerned, since she goes through extreme emotional reactions when they are separated—or when she anticipates separation. In the first anime, Sakuya frequently uses double entendres and innuendo when speaking to her brother, dismissing her words as jokes when he becomes really flustered.
Sakuya addresses her brother as Onii-sama (お兄様, Onii-sama?) as her sign of admiration. Her birthday is December 20, is a Sagittarian, and is the tallest of the sisters at 159 cm (about 5' 3").

(Source: Wikipedia)