Universal
Cultural · Seasonal
You
明けましておめでとうございます。今年もどうぞよろしくお願いします。
あけましておめでとうございます。ことしもどうぞよろしくおねがいします。
Happy New Year. I look forward to another wonderful year with you.
Romaji: Akemashite omedetou gozaimasu. Kotoshi mo douzo yoroshiku onegai shimasu. / Reply Romaji: Kochira koso, yoroshiku onegai itashimasu.
Reply
こちらこそ、よろしくお願いいたします。
こちらこそ、よろしくおねがいいたします。
Likewise, I look forward to working with you too.
Gesture & etiquette
A bow of about 15 degrees is standard for this greeting. In a business context, this may accompany the first meeting of the new year with colleagues or clients. Exchanging New Year's cards (年賀状) beforehand is the deeper cultural tradition.
This full two-part greeting is standard from January 1st through roughly January 7th (松の内). After that period, use 「本年もよろしくお願いします」without the 「明けまして」opener. Saying it too late in January is considered slightly awkward in formal settings.