Common Name

The website Anime Characters' Name Guide has a list of names taken from various anime including Ranma ½ and tells you how common a name is.

Saotome,Ranma

Ranma 1/2

Saotome

107

C

Ranma

E

The above is taken from the site. What it tells us is that Saotome is a minor name that you'll hear sometimes, the 107 is the number of times the name occurred in a South Kanto phone book, and that Ranma is a very rare name. The site is very useful for finding a Japanese name to use for a story.