Takeshi's name

I might be wrong, but it seems a lot of people think that "Aniki" actually is Takeshi's characters name? It's not!
Aniki is a slang term that rather refers to older Yakuza members and is a sign of respect. I think his real name is never shown or mentioned. I think we never know Kato's first name either. Curious enough, all the American gangsters only seem to be mentioned with their first names.