In Japanese, pronouns are not used much. If a sentence makes sense without a pronoun, it is usually omitted.
“Kare wa wakarimasu.” means “He understands.”, but if it were obvious who was being discussed, the sentence could be abbreviated to “Wakarimasu.”
The issue: Japanese has a lot of pronouns. For example, http://www.wa-pedia.com/language/japanese_personal_pronouns.shtml has a list of them. 21 of them mean “I”. I note that the list does not include “Atakushi”. 22!