It depends on what is called "Japanese".
If "Japanese" means the people who speak Japanese, it answers for itself. They've always spoken it, but for a long time they was no known written record. it was only when they started contacts (religious or trade) with china that they acquired a textual language. Since the earliest records of Japanese, the language hasn't gone dramatic changes, except in vocabulary.
If "Japanese" is the inhabitants of Japan, it is difficult to know, as aercheology does show the language spoken by the people producing the artifacts. Some people known through imperial chronicles might have spoken languages akin to Ainu, the language that was spoken in Hokkaido. In Hokkaido and Okinawa respectively, Japanese started being used in the XIXth and XXth century, after it was conquered and annexed.
To learn Japanese, you can start by studying basic vocabulary and grammar. Practice speaking with native speakers, watch Japanese movies or TV shows, and try using language-learning apps or websites. Consistent practice is key in improving your Japanese speaking skills.
go to where they are look for a book in the store called speaking Japanese or something like it hold on to it and start talking to them good luck!
A Japanese child would learn Japanese at the same age all other children would learn it from their parents. They start learning by listening, and would attempt to mimic their parents before their first birthday. At what age a child is fluent in Japanese varies according to their individual intelligence, language capability and education.
Speaking in Japanese
Because I told it to.
Japanese
no is the possessive particle as in 's
Pen or pencil, generally speaking.
Accents are relative things. To have a "Japanese" accent you have to be speaking a language other then Japanese. Japanese speaking characters can have an American accent or a Korean accent, or a dialect within Japanese like an Osakan accent or a Tokyo accent (assuming the intended audience isn't in Osaka or Tokyo). Generally Japanese shows do cast Japanese voice actors, however.
'Nante onna da' in casual speaking.
I know that Japan is the only Japanese speaking country. Unlike most cultures, it keeps it's language to itself. Most countries like America, the UK and France share their languages around the world. Japan's don't.
wen i was 5