Among other ways, you may simply say 'ureshii desu ka,' written in Japanese as: 嬉しいですか
"Watashi ha shiawase desu" is 'I am happy' in Japanese.
やった / yatta/ [hooray! Yes! I did it! etc] & 万歳 /ban zai/ [hooray! Praise be..! Long live..! etc] are most common ways.
Yorokonde
If you are saying "I am happy," you would use ureshii, or if you are saying happiness, you would say "shiawase"
Yukai Fi-to
You may say 'ureshii.'
In Japanese, they use the expression 'Merry Christmas,' which becomes 'merii kurisumasu' in Japanese.
Joyeuse saint Valentin or "Bonne saint Valentin
If you are saying "I am happy," you would use ureshii, or if you are saying happiness, you would say "shiawase"
Yukai Fi-to
happy birthday
You may say 'ureshii.'
In Japanese, they use the expression 'Merry Christmas,' which becomes 'merii kurisumasu' in Japanese.
jaoanese say itterashai
Otanjou-bi Omedetou Gozaimasu!
ureshiiYou may say 'ureshii.'
Yes it is.
I'm not too sure how to pronounce it, but you can hear the pronounciation of 'be happy' at the end of a song called 'Why did I fall in love with you' by Tohoshinki.
幸せな休日 Shiawase na kyūjitsu
ハッピーハウス : happii hausu. [The double p is pronounced geminated.]