How would you say "Thank you" in Japanese as a closing phrase?
A lot of Japanese language learners tend to use ありがとうございます(arigatou gozaimasu) as a closing phrase.
The English phrase "thank you" literally means ありがとうございます(arigatou gozaimasu), but that isn't correct for closing a letter.
You could say よろしくお願いします(yoroshiku onegai shimasu) in that case.
In addition, you could say よろしく(yoroshiku) as a closing phrase in a casual conversation, which means "thanks" in English.
However, if you mean "Thank you for talking with me," you could say 私と話してくれて、ありがとうございます(watashi to hanashite kurete arigatou gozaimasu).
In other words, if we use "Thank you (or Thanks) for 〜" as a closing phrase, we can say 〜てくれて「ありがとうございます(or ありがとう)」for closing.