I've heard it's good to leave price tags on a gift in Japan?

Question:

Is this true? Should I leave the tag on my gift when giving my present to my Japanese teacher?

Answer:

You should not do that in Japan, but In China, it's considered good manners to leave the price tag on a gift.
If you remove the tag, the recipient might assume that the gift was cheap.
The price of gifts matters in China, whereas, in Japan, the focus is on the "heart" put in to the gift.

In other words, the Chinese feel that the price of a gift reflects how much you care about the recipient, while the Japanese feel that your attention to the recipient's situation and preferences better display your affections, regardless of the cost.