The Seven Lucky Gods of Japan
There are several English translations of the phrase "Shichi Fukujin" and I have chosen one of the first I came across, that by Reiko Chiba and used by her as the title of her 1996 book on the subject. Much of what follows is based on her book, and on Miyata Noboru's compendium (Japanese).
The Seven Lucky Gods are:
as shrines and their origins are diverse: Daikokuten, Bishamonten and Benzaiten were originally Buddhists gods, Fukurokujů, and Jurōjin come from Taoism. Hotei is the only one of the group who was an actual person, in real life a Zen priest, who passed on in March 916, while Ebisu is considered to be of purely Japanese origin. Benzaiten, hailing from India, is the only female among them. They have all been recognized for a millennium or more.
Probably the first scholar to investigate the origins of the Seven Lucky Gods was Kida Teikichi. He traces the beginnings of the cult surrounding them to a quotation in a somewhat lesser known Buddhist text, the Sutra of the Humane King (仁王般若経, Nin-no-Hanya-kyō), as does the Buddhist Tendai sect on its (Japanese) home page. Note that the Nin-no-Hanya-kyō is one of the so-called apocryphal sutras, i.e. one which the anonymous author claimed was a translation from the original Indian language but was in fact composed in Chinese or Korean. The quotation is "難即滅七福即生”, shichi-nan-soku-tsume, shichi-fuku-soku-shō: a loose translation is that once the Seven Misfortunes have disappeared or been extinguished the Seven Happinesses will follow. For a country beginning to enjoy the Tokugawa peace after centuries of intermittent and sometimes intense civil war this must have been a very appealing concept. Kida thinks that the Seven Lucky Gods emerged in their present form towards the end of the Muromachi period in Kyōto. Bishamonten was one of the guardians of the Kurama Temple, Daikokuten was the three-headed statue of the god on Mt. Hiei, and Ebisu came from the Nishi-no-miya Jinja in what is now Kōbe. Benzaiten came from Chikubushima in Lake Biwa. The other three Chinese gods came from illustrations.
The home page of the Tendai sect also states that the person who first popularized the Seven Lucky Gods at the beginning of the Edo Period was the monk Tenkai (although the sentence is prefixed by the expression “it is said that.") Tenkai lived from 1536 to 1643 and rose to the highest possible rank in the Tendai sect. He was an influential figure in his time and in addition to being an advisor to the first Tokugawa Shōgun, Ieyasu, served as the liaison between the Shogunate and the Imperial Court. The story goes that Tenkai, along with telling Ieyasu that the peace he, Ieyasu, had finally brought to the country had brought with it happiness and prosperity, presented Ieyasu with an essay explaining the qualities associated with each of the Seven Lucky Gods, to wit, Jurōjin -longevity, Fukurokujů - popularity, Ebisu - integrity, Hotei - large quantity (of worldy goods), Bishamonten - power, Daikokuten - wealth, and Benzaiten - love and amiability. So taken with this was Ieyasu that he immediately commissioned the artist Kano Yasunobu to make a painting of the Seven Lucky Gods.
Wikipedia makes the following statement, but gives no source. “The Seven Gods of Fortune started being mentioned as a collective by the year 1420 in Fushimi, in order to imitate the processions of the Daimyo, the feudal lords of pre-modern Japan.”
"7" In the East and in the West
As the very concept of the Seven Lucky Gods makes clear it is not just in the West that seven is regarded as a lucky number. The Bible is often cited as the source of the lucky seven concept in the West, Buddhist scriptures can serve the same function in the East.).
In addition to the Nin-no-Hanya-kyō quoted above there are numerous other uses of seven in Buddhism, among them,
七仏 (shichi-butsu) “The seven previous incarnations of Buddha”
Vipassī, Sikhī, Vessabhū, Kakusandha, Koṇāgamana, Kassapa, Gautama
七祖 (shichi-so) “The seven patriarchs”
Nāgārjuna, Vasubandhu, Tánluán, Daochuo, Shandao, Genshin, Hōnen
七宝 (shippō) “The seven treasures”
gold, silver, pearls, agate, crystal, coral, lapis lazuli
Miyata says that examples of such usages are too many to count, and with 54 examples in the Book of Revelations alone the same is doubtless true in the West. But probably to a lesser extent in China. Kida goes on to say that the Seven Lucky Gods were probably modelled on the Chinese “Seven Sages of the Bamboo Grove” (竹林の七賢人”chikurin-no-shichiken”). Although eight is probably considered to be the lucky number in popular Chinese culture, seven is far from bereft of auspicious associations:
七曜 (shichi-yō) “The seven luminaries”
sun, moon, Mercury, Venus, Mars, Jupiter, Saturn
七情 (shichi-jō) “The seven emotions”
1a seven emotions, in The Book of Rites: joy, anger, sorrow, fear, love, hate, desire
1b seven emotions in Buddhism: joy, anger, sorrow, pleasure, love, hate, desire
2 “The seven effects” (of a traditional Chinese medicine, the terms are beyond my powers of translation)