Hatsuyume

Hatsuyume (初夢) is the Japanese word for the first dream had in the new year. Traditionally, the contents of the dream would foretell the luck of the dreamer in the ensuing year. In Japan, the night of December 31 was often passed without sleeping, thus the hatsuyume was often the dream seen the night of January 1. This explains why January 2 (the day after the night of the "first dream") is known as Hatsuyume in the traditional Japanese calendar.