Kodachi Kuno is the deranged younger sister of Tatewaki Kuno. After being saved from falling off a roof by Ranma she immediately fell for him. She is probably Ranma's most troublesome love interest because she constantly tries to slip him paralysising agents in his food so that she can keep him all for herself.
Kodachi attends St. Hebereke School for Girls, and is the captain of the rythmic gymnastics squad there. She is a capable martial artist as well, and combines the two sports into a unique fighting form.
She has the same feelings towards Akane as her brother does for Ranma. She is very jealous of the fact that Ranma lives with the Tendos, and utterly despises Akane for being engaged to Ranma.
Like her brother, she has a flair for drama, and often speaks with a very refined aire. She can also be equally difficult to deal with and quite tenacious when it comes to getting what she wants, which is usually Ranma.
The Meaning Behind the Name
A "Kodachi" is a type of sword. The joke here is that her brother's name, Tatewaki, means "bringing a sword" which refers to the fact that he always carries a sword. Kuno can be broken down to mean "Nine Abilities," possibly a joke about how talented she believes herself to be.
Saeko Shimazu & Teryl Rothery
Saeko Shimazu has been involved in two other Rumiko Takahashi anime. She played Shinobu Miyake in Urusei Yatsura and Sayoko Kuroki in Maison Ikkoku and Princess Abi in Inuyasha. Her non-Takahashi roles include Yura in Dirty Pair and Midori Oohara in City Hunter.
Teryl Rothery provided the spoiled voice of Kodachi for the majority of the series. Her other voice work includes A-ko Magami in the Project A-ko series and Mai on Dragon Ball and also Princess Abi in Inuyasha. Teryl left to pursue live action work on the sci-fi series Stargate SG-1 and was replaced by Sylvia Zaradick for Kodachi's few remaining appearances.