day of the Dragon
Refers to a day in the traditional Japanese sexagenary cycle (eto) that corresponds to the Dragon (辰). Often associated with customs such as visiting shrines on the first Dragon day of the year.
初辰の日には、多くの人が神社に参拝する。
On the first day of the Dragon, many people visit shrines.
Compound of 辰 (tatsu, 'Dragon', the fifth sign of the Chinese zodiac) and の日 (no hi, 'day of'). The reading たつ is the native Japanese name for the Dragon sign.