On the day of the Dragon Boat Festival, you may have heard that it is good to brew calamus and drink it, or put it in bathwater and soak in it. Calamus has long been thought to be an herb that wards off illness and evil spirits.

The Boys' Festival originally from China is called "Bad Moon" as diseases were prone to spreading in the 5th month of the lunar calendar. In particular, May 5th is considered a day of strong "Yin" energy because the odd number "5" symbolizing "Yang" overlaps in the Yin and Yang theory. Therefore, it is believed that the custom of purifying oneself with iris to ward off misfortune was born.