There are several ways to say “lucky” in Japanese. I’ll introduce 7 words and phrases and the difference between them.
Kouun (Good Luck)
KOUUN is the most common way to mean good luck. KOU is happy, and UN stands for luck.
The single letter UN can mean luck too, but if you want to indicate good luck, Kouun can clearly mean that!
Kyouun (Strong Luck)
KYOUUN is a similar word to Kouun. KYOU stands for “strong”. This word has a nuance that you can survive a bad situation or win a battle with your powerful luck.
This word has a nuance that you can perform better than you really are.
Un ga Ii (Have Good Luck, Fortunate)
UN GA II is a phrase used for meaning someone with good luck. You can say “Watashi ha un ga ii” if you want to mean you’re fortunate.
Tsuki (Short-term Luck)
TSUKI stands for luck but it’s only blind luck. It doesn’t last and you’re fortunate by chance. Here are some usages for this word.
Tsuki ga Aru (in Luck)
If you want to say you are lucky today, you can say “Tsuki ga aru”, meaning “I have Tsuki (luck)”
Tsuiteru (in Luck in a more casual way)
Tsuiteru is a more casual way to mean “I have Tsuki”. Frequently used in spoken Japanese.
The English word “lucky” is well known in Japan. Most Japanese can understand it, and the meaning is the same as the English word. It’s written in Katakana and is used commonly in Japan.