The oldest of the Tendo girls, Kasumi took over the role of the "mother"of the house when her mother died when Kasumi was young., Kasumi does all the house work and cooking for the Tendo family. Good thing too because unlike her sister Akane, Kasumi's cooking is quite tasty. That's not to say, however, that she does not have her faults (if thats what you want to call them).
Kasumi is a bit naive and always looks for the good in everyone. She never EVER gets mad, but sometimes (rarely) she does show her annoyance. On top of all that, she seems completely oblivious to all the strange things that happen around the Tendo Dojo, which is quite often.
Though she isn't a forceful person, she is constantly trying to persuede Ranma and Akane to get along better with each other. However, her plans are never as forcible on Ranma or Akane as her father, Soun Tendo, and Gemna Saotome's plans are.