The Japanese language doesn't like pronouns. Around the same time that English speakers stop saying, "The mistress beat her slave with a wickedly barbed whip," and start saying, "She beat him with it," the Japanese start omitting the references altogether. The Japanese version of the second sentence might be as simple as a single verb: "Beat." (Because you can't omit the verb, you know. Unless you're trying to be refined or elliptical. But more on that elsewhere.) Confusing? Can be. Japanese speakers rely upon context to make their meaning clear; in fact, it sounds gauche to not drop references as soon as the context is clear.
Despite the language's unfriendliness to pronouns, Japanese contains dozens and dozens of ways to say "I," "you," "he," "she," "them," and "it." (By one count, there are almost 100 ways to say "I.") This is because even though pronouns are less frequent in Japanese than in English, they are more crucial in setting the tone of a sentence. Every pronoun has a slightly different shade of politeness and meaning, and is used in slightly different situations by slightly different people.
One last note: Japanese does not inflect pronouns the way English does, so I, me, and my are all the same word. Same for you, your, and yours; she, her, and hers; and so forth.
| used mainly by women
used mainly by men