Tsukasa Tsukisaki

Yuu’s younger sister by one year. She is a vibrant, mayhem-causing character that loves attention. She is more sexually mature then her older sister and often embarrasses Mugi by correctly guessing his perverted thoughts. She has a propensity with coming up with complex plans and changing games to have a sexual variation. She chose to move to America with her mother, but often comes back to visit. During her last visit, her body has matured to the point that if she wears a wig she can impersonate her older sister almost perfectly. (Wikipedia)