Naga at Bungkarn province

Naga is one of the animals in the celestial realms. One of them had seen the Lord Buddha coming back from giving the sermon to his mother in the Tavatimsa Heaven, it believed more and began to blow its fire to worship the Lord Buddha on the last day of Buddhist Lent. However, the naga in this new did not blow fire but the people and visitors were interested in it. Why?