Originally she was a nice girl, but following the death of her parents she disregarded Saki as her sister and became depressed. Then she started hating on the world and swore revenge on all who defied her.
As stated earlier, she was the best big sister a kid could have. However, when her parents died when she was 14, she ran away and disowned Saki. She grew up in the mountains with her stepfather, Samurai Jack. When she was 22 she grew an intense hatred for herself and the world, but before she could do anything important she was killed in the Vietnam War. Her rudeness towards Saki was what got her hated throughout most of society.
She has red hair.
Saki looks exactly like her.
Oh, and she needs a haircut.
I'M TELLING YOU STUFF YOU ALREADY KNOW!!