Kesa is a cloth robe worn by a Buddhist priest
It is a transliteration of the Sanskrit word Kasaya that means 'cloudy color.'
It is also called funzoe or fukudenne.
It was originally a cloth worn by a Buddhist priest in India. In Buddhism, priests were prohibited from having any private possessions that could have value; clothing were no exception. Therefore, a cloth to cover the body was made by collecting and sewing together rags that had lost their value and were thrown away, or something like using pieces of cloth for wiping filth (funzo - literally, wiping excrement). In order to distinguish the monks from lay believers (wearing white cloth), the cloth was dyed again into ocher or bluish black using plants or the rust of metals. The name in Sanskrit originated from this color. There are three types: Andae, which corresponds to working wear, uttaraso that corresponds to an everyday cloth, and sogyari that corresponds to a formal or visit cloth. Together with bowl that is used for eating and takuhatsu (a traditional form of begging, common to Buddhist monks in Japan), these are known as sanneippatsu and deemed necessary articles for a priest.
In accprdance with propagation of Buddhism to cold areas, underwear was used and, when it arrived in China, it had lost its original usage and become decorative, symbolizing the wearer as a priest. After it was brought into Japan, cloths with various colors or baldachin were used and it became a symbol of the rank or the privilege of the monk in combination.
In particular, until the Edo period, permission by the emperor was required to wear 'shie (purple robe for high-ranking priests)' or 'murasakikesa (purple kesa).'
On the other hand, because general priests used black clothing, they came to be called 'kokue (black clothing).'
Formerly, a kesa was worn to cover the whole body, but, at present, it is hung to reveal the right shoulder excluding special situations (hendan uken). This is to show worship and feelings of love and veneration for Buddha in comparison with Nyorai (Tathagata) who wears a kesa to cover both shoulders (tsu ken). The reason why the left shoulder is hidden is that the left hand is deemed unclean in Buddhism.
While there are a lot of variations of shape depending on the religious sect or usage, they still share a common method of sewing together small pieces of cloth. A strip of vertically joined small pieces of cloth is called jo (strip) and kesa is made by joining multiple jo horizontally. The number of jo is usually five, seven or nine; the more jo is used, the more valuable the kesa is deemed. In ancient times, kesa with fifteen or twenty-three jo existed.
Because pieces of cloth sewn together look like paddy fields, it is sometimes called Fukudenne (lucky paddy field clothing). According to one view, it originated from the fact that Hashinoku-o (King Pasenadi) of Sravasti, who became a follower of Shakyamuni, mistakenly worshipped Brahmanism by mistaking a disciple of the Brahmanism for that of the Buddha.
As a result, he asked that a rule be made to govern clothing, so Shakyamuni said to Ananda beside him, pointing the paddy fields, 'How about making it like that.'
According to another view, it originated from the concept of Fukuden (the world's unsurpassed Field of Merit) that teaches people to gain merit by doing good deeds.
In the Zen sect, kesa is positive proof of shiho (the dharma founded by Shakyamuni is inherited by a disciple from a priest master). When the priest master judges that training of the disciple has been successfully completed, he teaches the disciple the core of the dharma, and gives the disciple kesa and Jihatsu (nesting set of bowls with which a priest in training eat) that were inherited from the founder of the sect, in proof of the completion. The expression 'ihatsu wo tsugu (to assume the responsibilities and duties of one's master)' originates from this.
In some sects, a simplified-type kesa called wagesa is used by laypersons when taking part in a Buddhist mass.
Occasionally, some persons are named 'Kesao'. It is derived from the fact that the person in question was born with the umbilical cord coiled around his neck in his mothers womb and looks like a person wearing wagesa. Such conditions are very dangerous, and the rate of death among such infants is high. This name is given as an incantation to ensure the growth of a newborn.