Kore wa goteinei ni, osoreirimasu.
This is very kind of you. I’m honored.
When you receive a gift, you must be mindful of the proper form for showing gratitude—a casual word or two of thanks won’t do. It’s common, for example, to indicate that you are simply overwhelmed, even to the point of apologizing (for the trouble the giver has gone through to select it) and hinting that you really couldn’t possibly accept it.
Konna koto o shite itadaku to moushiwake nakute…
Oh, this is so very kind of you, but I’m afraid, really …
Iwatte kudasaru okimochi dake de juubun desu no ni konna mono made choudai shite …
Your good wishes alone are precious enough, but to receive such a lovely gift as well …
The gift-giver, playing his part in this ritual, will deprecate his gift as a way of urging you to accept it.
Iie, taishita mono de mo arimasen kara …
Oh, hardly. It’s really nothing to make a fuss over.
At this point it would be possible to end the drama by simply saying you’ll park your good manners and take the loot.
Sore de wa enryo naku choudai shimasu.
In that case, I’ll dispense with the formalities and accept it.
You will communicate more of a sense of gratitude, however, if you emphasize your pleasure rather than your capitulation.
Sore de wa yorokonde choudai shimasu.
In that case, I happily accept your gift.
Finally, you are actually ready to say thanks, and you should do so in way that lets the gift-giver know you fully appreciate the feeling behind the gift.
Okokoro no komotta oshina o arigatou gozaimasu.
Thank you for such a thoughtful gift.
Traditionally, gift-giving and gift-receiving have been linked in a quid pro quo arrangement that is still widely observed, to the extent that even now people often automatically associate the act of accepting a gift with the obligation to give one in return. Owing to this aspect of the transaction, there are actually plenty of people who would just as soon not receive gifts at all. There are also occasions when you are not expected to (and should not) give a return gift: when you are given a present to take home from a reception or banquet; when you receive a farewell gift, a get-well present, a graduation present, or the like from someone older or in a senior position; or when you receive a midsummer gift, a year-end gift, or a present given in thanks for a favor you did from someone younger or in a lower position.
Some people feel obligated to give gifts in return for get-well gifts or presents given to them to celebrate a family occasion. In the former case, since the fact of one’s recovery is presumably being celebrated by all one’s friends, it’s not necessarily good form to give presents only to people from whom you received them, and in the latter case return presents are simply unnecessary.
– Source: A handbook of common Japanese phrases –