TOKYO (NYTIMES) - The day before Mr Shinzo Abe was assassinated, Tetsuya Yamagami sent a letter saying that the Unification Church had ruined his life, "destroying (his) family and driving it into bankruptcy".

Yamagami's mother had been a member of the church for more than two decades, making prodigious donations over her family's objections.

"It's no exaggeration to say that my experience with it during that time continues to distort my whole life," he wrote to a blogger who covered the church. Japanese police have confirmed that he sent the letter.

The next day, Mr Abe was dead, shot at close range with an improvised gun while campaigning in the city of Nara, Japan.

Police have charged Yamagami with murder, saying he was angry at a "certain group" and decided to target Mr Abe, the former prime minister of Japan.

The authorities have not named the group, but a Unification Church spokesman said that Yamagami was most likely referring to them. It remains unclear why Yamagami directed his animus at Mr Abe.

The July 8 shooting has thrust the church's legal troubles back into the national dialogue, in particular its battles with families who said they had been impoverished by large donations. Those payments were among billions of dollars in revenue from Japan that helped finance much of the church's global political and business ambitions.

In one judgment from 2016, a Tokyo civil court awarded more than US$270,000 (S$375,000) in damages to the former husband of a church member, after she donated his inheritance, salary and retirement funds to the group to "save" him and his ancestors from damnation.

In another civil case from 2020, a judge ordered the church and other defendants to pay damages to a woman after members had convinced her that her child's cancer was caused by familial sins. On their advice, she spent tens of thousands of dollars on church goods and services, like researching her family history and buying blessings.

Last week, church officials said they had struck an agreement in 2009 with the family of Yamagami's mother to repay 50 million yen (S$510,000) in donations she had made over the years. In an interview, Yamagami's uncle said she had given at least 100 million yen.

Many families have settled complaints against the church through court-arbitrated agreements, according to Mr Hiroshi Watanabe, a lawyer who has negotiated some of them.

Ms Eri Kayoda, 28, grew up in a household devoted to the Unification Church.

She said that her mother gave the church an inheritance and the proceeds from the sale of their home. The family had to squeeze into a tiny Tokyo apartment decorated with pricey Unification Church books and vases thought to bring good fortune, she said.

In middle school, Ms Kayoda said, she began keeping a close eye on her parents' finances and convinced them to save for a car and a home. Her mother now donates modestly. While Ms Kayoda condemned Mr Abe's shooting, she said she hoped it would draw attention to the "many cases of families that have been destroyed".

Mr Susumu Sato, a spokesman for the Unification Church in Japan, said that some members had encouraged followers to donate excessively, but that most donors were motivated by their faith.

"Nowadays, it seems unthinkable, but those people believed in God," said Mr Sato, who said he feared church members would become scapegoats for Mr Abe's death.

Reverend Moon Sun-myung founded the Unification Church in South Korea in 1954. Five years later, he opened its first overseas branch, in Japan, which quickly became the church's largest revenue source.

Mr Abe's grandfather, Mr Nobusuke Kishi, a former prime minister, appeared at events sponsored by a group that Rev Moon established to fight communism.

Decades later, in 2021, Mr Abe spoke by video feed to a conference in Seoul, South Korea, sponsored by a church-affiliated non-profit organisation, praising its "focus and emphasis on family values".

An ardent Korean nationalist, Rev Moon was educated in Japan while his own country lived under its colonial rule. His theology reflected his ambivalence towards Japan, describing it in his sermons as both a potential saviour and a satanic power.

During visits, Rev Moon warned his Japanese followers that they were steeped in sin and exhorted them to sacrifice everything for the church.

"Each of you needs to restore, through paying indemnity, the sins committed by your ancestors in history," he told a group of believers in 1973, instructing them to "shed blood, sweat and tears".

Hundreds of thousands heeded his call. By the mid-1980s, billions of dollars in donations had flowed from Japanese families into the church's coffers.

Rev Moon used the money to build a sprawling business empire and a network of non-profit organisations and media outlets, such as The Washington Times, that he leveraged for political influence.

Families were asked to make constant donations and pay steep fees to purchase various religious services and leather-bound volumes of Rev Moon's teachings, according to court judgments handed down in subsequent civil suits against the group.

Businesses connected to the church sometimes used high-pressure sales tactics to gather even more funds.

Judgments from civil suits describe how followers used warnings of ancestral curses to sell products like decorative vases imported from South Korea. The church decided whom its followers would marry and sent thousands of them - mostly women - abroad to become the spouses of church members.

By the early 1990s, Rev Moon's power in Japan had peaked. In 1995, sarin gas attacks by members of the religious cult Aum Shinrikyo created a backlash against what are referred to in the country as new religions. Suspicion of the Unification Church hardened as former followers published tell-all accounts and lawsuits began to mount.

The National Network of Lawyers Against Spiritual Sales, a group that has spent decades crusading against the church, started receiving complaints about it in the late 1980s. It eventually collected more than 34,000, claiming damages in excess of US$900 million.

As criticism built, the Unification Church went on the offensive, arguing that years of negative attention had led to its followers' persecution.

In one case, a young man, Mr Toru Goto, was confined in a Tokyo apartment for more than 12 years as family members attempted to "deprogramme" him, according to a civil suit he filed against his parents and others in the city.

In the spring of 2009, Tokyo police raided a church-affiliated business that pushed customers to buy traditional seals, often used for documents, at steep mark-ups. The arrests resulted in fines against five employees and suspended prison sentences for two executives.

Fearing that the Japanese government would revoke its legal status, the church announced new controls on recruiting and donating.

In the years since, the church's power and influence in Japan - as well as the complaints against it - have ebbed.

But "even now, there are a lot of people like Yamagami's family", said Mr Yoshifu Arita, a member of Parliament who has frequently spoken out about the issue. "Japanese society just doesn't see them."

Yamagami, however, never lost sight of the Unification Church. His mother's actions had "plunged my brother, my sister and me into hell", he wrote on a Twitter account. The account name was included in the letter he sent before Mr Abe's shooting.

Amid anti-Korean screeds, misogynistic musings about incel culture and commentary on Japanese politics, the account - which has been suspended - describes a painful childhood and a seething fury at his mother's allegiance to the Unification Church. He blamed the relationship for his own failings in life.

Yamagami was born into a wealthy family, but when he was four, his father killed himself. A decade later, his grandfather died suddenly, leaving no one to stop "my mother who had been channelling money to the Unification Church", Yamagami wrote on Twitter.

She "wrapped our whole family up in it and self-destructed", he wrote.

In the letter he sent before the shooting, Yamagami said he had spent years dreaming of revenge, but had become convinced that attacking the church would accomplish nothing.

Mr Abe is "not my enemy," Yamagami wrote, "he's nothing more than one of the Unification Church's most powerful sympathisers." But, he added, "I no longer have the luxury to think about the political meaning or consequences that Abe's death will bring."