We found this display in the post office in Shibuya.
KitKat Mail allows you to mail chocolate with a message on its package in collaboration with Japan Post. During this season, the messages are usually words of encouragement for newly graduates or people starting new jobs or schools. This year the campaign was promoted by Japanese band DISH and rugby coach Michael Ritchie.
In Japan KitKat is famous for bringing good luck as it sounds similar to the Japanese “Kitto Katsu”(I will win for sure).