âTemples will sell you 10 yen candles for 100 yen,â said Mr. Soko, 39. âTheyâre protecting their own interests.â
Such arguments will be familiar to anyone who has watched e-commerce companies upend other parts of the economy, from book publishing to airlines, taxis and hotels.
In Japan, even in areas far less sensitive than religion, newcomers often receive a chilly reception, and start-ups are rarer than in other rich countries. Among the explanations are a scarcity of venture capital, the political clout wielded by established businesses and a culture that values stability over the creative destruction that drives growth in countries like the United States.
Credit Ko Sasaki for The New York Times
Yet religion may prove to be an exception. It is so opaque â and so removed from the day-to-day lives of many modern Japanese â that a little technological disruption may prove welcome.
The stakes are material as well as spiritual. As with religious institutions in many other countries, temples in Japan receive generous tax breaks.
âIf it becomes a fee for services instead of a donation, and the government says, âO.K., weâre going to tax you like a regular business,â how are we supposed to object?â said Hanyu Kakubo, a priest at the Japan Buddhist Federation, which opposes obosan-bin.
As with adherents of many religions, Buddhists typically give donations to priests for their services. Proponents of obosan-bin argue that conventional temples already operate like businesses â ones that put customers at a disadvantage though murky pricing. The amount is left up to the donor, a custom that leads many to overpay, Mr. Soko said.
âThey donât want to make things clear,â he said.
Much of the reaction in Japan to obosan-bin has been positive, for equally familiar reasons: It offers convenience and low, predictable prices.
âThere has been fierce criticism from the Buddhist world, but these days many people are abandoning religious funerals altogether,â said Noriyuki Ueda, an anthropologist who studies Buddhism at Tokyo Institute of Technology. âAt least people using obosan-bin think having a priest is necessary.â
Mr. Kakubo of the Buddhist federation conceded that many temples had done a poor job of adapting.
âWe need to reflect on the fact that weâve created this situation where people feel that they have to turn to the internet,â he said, adding: âAre we protecting our vested interests? Yes, obviously.â
The process of booking a priest on Amazon can feel disconcertingly secular. Users click on one of several options and add it to a virtual shopping cart, the same way they would a juicer or a pair of shoes. Prices are fixed. A basic memorial ceremony at the home of the deceased costs Â¥35,000, or about $ 344.
The most expensive package, with a second service at a cemetery and the granting of a special posthumous Buddhist name, costs Â¥65,000.
Obosan-bin was originally the brainchild of Minrevi, a for-profit internet start-up. Before signing on with Amazon last year, it built a network of 400 priests and took bookings on its own website, which it still maintains, as well as by phone. It said it keeps about 30 percent of the fees it collects; the rest goes to the priest.
The company has added another 100 priests to meet demand generated by its new partnership with Amazon, said Jumpei Masano, a spokesman. It expects bookings to increase by 20 percent this year, to around 12,000.
Credit Ko Sasaki for The New York Times
âA lot of people donât have any connection with a temple, so they donât know where to turn or what to do when they have to arrange a funeral,â Mr. Masano said. âWe saw there was a need.â
Amazon declined to comment. In a written reply to the Buddhist association in April, reported by Japanese news media, it said its goal was âto provide as much information as possibleâ to its users so they âcan make their own decisions.â
When Mr. Kaiâs wife, Chieko, died, her funeral was held at a secular funeral parlor. But for the anniversary, Mr. Kai decided he wanted a priest.
âWe had a big altar in the house where I grew up, but not here,â he said, gesturing around his small, tidy apartment in a public housing complex.
He said he rarely thought about religion until his wifeâs death. In the years after World War II, rural dwellers like Mr. Kai poured into places like Sakai, an industrial suburb of Osaka. Relatively few bothered to put down new religious roots in the city.
Today, 70 percent of Japanese identify themselves in surveys as nonreligious or atheist, though many said they still followed traditional religious customs such as going to a Shinto shrine at New Year or periodically visiting their ancestorsâ graves.
Mr. Kaiâs daughter-in-law found Minreviâs website. Her only request was that the priest should belong to the order to which the Kai family had belonged in his hometown, in Ehime Prefecture on the island of Shikoku.
Mr. Soko fit the bill. At the ceremony, which took place in Mr. Kaiâs apartment, Mr. Soko delivered a short homily about faith and remembering the dead.
The Kais seemed satisfied: They said they would request Mr. Soko for the next important death anniversary, in two yearsâ time.
Mr. Soko said innovations like obosan-bin are vital to Buddhismâs survival. Most templesâ dues-paying congregations are shrinking as a result of social change and rural depopulation.
Incomes are shrinking, too. Revenue at temples and other religious institutions has fallen by a third in the last 20 years, mostly because of a drop in regular donations from long-term members, according to the governmentâs Agency for Cultural Affairs.
âIn the seminary, they teach you to chant sutras, but they donât tell you anything about how to manage a temple,â Mr. Soko said. âWe have to try new things.â