In Japanese, you say "thank you" as:

• ありがとう (Arigatou) – casual, used with friends or people you know well.
• ありがとうございます (Arigatou gozaimasu) – more polite and formal, suitable for most situations.
• どうもありがとうございます (Doumo arigatou gozaimasu) – very polite and expresses deeper gratitude.

If you want to say "thank you very much," you can say:

• どうも (Doumo) – very casual, often just "thanks."
• どうもありがとう (Doumo arigatou) – casual but a bit more emphasis.
• どうもありがとうございます (Doumo arigatou gozaimasu) – very polite and formal.

Would you like to know how to say it in a specific context or with a particular level of formality?