Japanese people like to import from different culture. Historically, Japanese favorite food Ramen, or noodle soup originates in China. The interesting point is that Japanese people import from its origin and arrange it to Japanese taste. Ice cream is also imported from foreign country. The popular Häagen-Dazs is from the United States but is liked by many Japanese people. Have a look at the picture. This is green Tea flavor which is extremely popular in Japan. The flavor comes from a specific type of green tea used in the Japanese tea ceremony, and it has been produced by the famous foreign ice cream vendors such as Häagen-Dazs and Baskin Robbins. I do not assume all foreigners enjoy the taste since it is particularly aimed at customers in East Asian countries.
I have watched a Japanese film: Tampopo(dandelion) directed by Juzo Itami which dealt with Japanese food culture. It is very interesting that the film does not show rice which the essential food of Japanese people throughout the movie, but many mainstream foods Japanese people love such as ramen, omrice (omelet which contain ketchup-seasoned chicken rice), and spaghetti. These foods are certainly loved by Japanese, and a number of restaurants in Japan have these in their menu, but they all derive from foreign cultures.
Historically, Japanese culture has been always affected by the continuing influxing foreign cultures. This green tea flavored ice cream symbolizes Japan's assimilative characteristic with foreign influences.