The Double-Ninth Day is actually a vacation associated with driving away risk and showing respect to ancestor merely like Ching Ming.
The story of Chung Yeung Festival
Quite a long time ago there appeared a devil of annoyance in the Ruhe River. A youngster named Heng Jing was educated through an old Taoist how to conquer this annoyance. The priest told the lad that the devil would return in the 9th of September and told him to go back and save the village. He did this by telling them all to go climb up a mountain, then he fooled the plague devil with some strong Chinese wine made from Chrysanthemum flowers while the villagers were safe and killed the devil.
The people of Hong Kong observe the custom of trekking up hills and mountains using their loved ones. There, they appreciate the holiday with picnics including chrysanthemum wine. They also decorate zyhuyu plants to drive away sickness. The Chung Yeung Festival is also a day for paying respect to ancestors. Hence, just as through the Ching Ming Festival, families visit graves, clean out the tombs, and hold gatherings at burial sites.