Japanese phrase
___までにお返事します。 ___ ma de ni o hen ji shi ma su
Meaning
I will reply by ___.
When to use it
Promises a reply by a specific time. The polite expression fits professional conversations and other formal exchanges.
Example dialogue
いつまでにお返事をいただけますか？ i tsu ma de ni o hen ji o i ta da ke ma su ka
By when can I expect a reply?
明日までにお返事します。 ashita ma de ni o hen ji shi ma su
I will reply by tomorrow.