Haishi Day (or Cold Food Day) is the very day just before the Qingming Festival (also named Tomb Sweeping Day, or Clear and Bright Festival). On the Hanshi day every year, no fire or smoke is allowed and people shall eat cold food for the whole day.

According to the legend, the day is in memory of Jie Zhitui who lived in the Spring and Autumn Period (770-476BC).

Jie was a good official in the Jin State, working for Crown Prince Chong'er. When Jin State was in turmoil, Chong'er was forced to leave for other states with his henchmen, including Jie. On the way of exile they went through all kinds of hardships and difficulties. To save the starving Chong'er, Jie even cut the flesh off his own leg and boiled for Chong'er. After ascending the throne, Chong'er began to forget Jie by and by. Jie was so sad that he prepared to leave and live in seclusion with his mother in mountains.