Shampoo
It be Shampoo the lovely catgirl to be more specific.  One of the few splendors of Ranma 1/2 well that is besides the comedy but seriosly Shampoo runs around in her pyjamas which is a great thing i think we will all agree to that especially the members of the Shampoo worship mailing list  and i just happen to be a member......what a surprise huh but anyways last but not least i must add her ditsy attidute which is a major turn on ide say she would willingly do anything.  Happy me.
Shampoo is an Amazon from the Amazon village, Joketzukoku.  When Ranma and Genma had left Jusenkyo after they had fallen, they chased each other to Joketzukoku, where an annual contest was being held.  Since they had just been dunked, they were one hungry girl-panda pair, and they ate a small feast which happened to be the prize for the winner of the contest.  Shampoo had won, and, infuriated that her prize had been eaten by an outsider, challenged the female Ranma.  Ranma beat Shampoo, adding injury to insult, and Shampoo gave Ranma the "Kiss Of Death", which meant that Shampoo would hunt her forever and kill her.
                Shampoo followed Ranma and Genma to Nerima  where she found  the male Ranma.  He accidentally defeated her (he didn't want to fight her), and Shampoo said "Wo Ai Ni" which means I love you In Chinese.  It would later be found that Amazon law states if a woman is defeated by another woman, she must kill her, but if a woman is defeated by a man, she must make him her husband.  Shampoo continued to fawn over the male Ranma, while trying to kill the female Ranma, until Ranma revealed to Shampoo that he and her are one and the same (try sayin' that four times fast).  But Shampoo had fallen in love with Ranma, and, with conflicting emotions, said "Bie Liao" which means we'll never meet again, and left.
                Shampoo returned to the village, and her great-grandmother faced her atop the poles of Jusenkyo, where she said Shampoo had brought shame to the tribe by returning in defeat, and proceeded to train her all over again.  Well, she got knocked into the Spring of Drowned Cat, Maonichuan.  She therefore undergoes the Jusenkyo curse.
Shampoo + cold water = 
 Shampoo (cat) + hot water =
                Shampoo travelled back to Nerima with her great-grandmother and used the curse to sneak into the Tendo dojo as a cat.  She broke into Ranma's bath to catch him, but Ranma went phobic when he saw her because of his ailurophobia(he's afraid of cats).
                Shampoo and her great-grandmother run a ramen restaurant called the Cat Cafe in Nerima, and Shampoo often tries to win Ranma's affections, or, in most cases, scheme for them.  She is trained in Amazon combat, and, if fighting, will be armed with a sword or "bonboris", a pair of round mallets.
Back to the Don...Nihao, Ranma!