One of the more esoteric features of the calendar are the six auspicious days known as rokki (or rokuyo; literally "six days"). Like much else in the temporal realm, the system made its way to Japan from China in the 14th century and has been prominent since the 18th century. It has continued to exert a strong, if declining, influence on the movements of daily life. On taian, the most favorable of the six days, conditions throughout the day and night are optimum for festive occasions. In contrast, butsumetsu is to be avoided at all costs, as any business opened or events planned are likely to come to no good end. Between the two extremes are sensho, a good day for urgent business and lawsuits, but only if undertaken in the morning; tomobiki, which is auspicious in all but the afternoon and should be avoided for Buddhist ceremonies and funerals; senbu does not bode well for public affairs or urgent business, but if a task is approached in a calm state of mind, the afternoon should prove fortuitous; and at the risk of disturbing an angry god, important activities should be avoided on shakko except at noon.
The rokuyō are a series of six days that predict whether there will be good or bad fortune during that day. The rokuyō are still commonly found on Japanese calendars and are often used to plan weddings and funerals. The rokuyō are also known as the rokki. In order, they are:
The rokuyō days are easily calculated from the Japanese Lunisolar calendar. Lunisolar January 1st is always senshō, with the days following in the order given above until the end of the month. Thus, January 2nd is tomobiki, January 3rd is senbu, and so on. Lunisolar February 1st restarts the sequence at tomobiki. Lunisolar March 1st restarts at senbu, and so on for each month. The last six months repeat the patterns of the first six, so July 1st = senshō and December 1st is shakkō.