To say "How are you?" in Japanese, you can use:

• お元気ですか？ (O-genki desu ka?)
  This is the polite and common way to ask "How are you?"

  • お (O) is an honorific prefix
  • 元気 (genki) means "well" or "healthy"
  • ですか (desu ka) turns it into a polite question

In casual situations, among friends, you can simply say:

• 元気？ (Genki?)
  This means "Are you well?" or "How are you?" in a more informal tone.

If you want to be even more casual, you might hear:

• 調子はどう？ (Choushi wa dou?)
  Meaning "How’s it going?" or "How are things?"

Let me know if you want to learn how to respond to this question!