Hekui
A malevolent spirit (associated with the Xu branch) at the direction opposite the month's ruler (month branch). Traditionally, days under its influence were considered inauspicious for travel, marriage, or starting a business.
Hekui is the malevolent spirit located at the direction directly opposite the month's ruling branch. In the traditional Chinese system of day selection (择日), days ruled by Hekui were considered highly inauspicious. Traditionally, these days were avoided for important activities such as long journeys, marriages, and grand openings for businesses. Its malevolent nature is derived from the clashing ('chong') force of opposition and disruption, with the belief that undertaking actions on such days would easily lead to obstacles, conflicts, or failure.