Shinzo Abe was renowned for his economic policies and nationalistic bent, but his legacy also includes an association with conservative religious groups and there is some evidence it is this reputation that made him a target.
His alleged assassin, Tetsuya Yamagami, sought out Mr Abe, researched campaign events he would be at, made a gun, and, on Friday afternoon, shot and killed the political giant.
Yamagami, 41, told Japanese police his mother was a member of a religious organisation and their family had been financially ruined after she made a "huge donation", Japanese media reported, citing police sources.
After the shooting, Japanese police did not release the name of the religious organisation, but pressure built as Japanese tabloids and the Washington Post named the group in question: The Family Federation for World Peace and Unification, known colloquially as the Unification Church.
Then, on Monday afternoon, church officials held a small press conference, confirming Yamagami's mother was a member of their organisation, but refused to detail how much money she had given, citing the ongoing investigation.
"Regarding Tetsuya Yamagami's motivation for his crime and the reported issue of donations by his mother, we will refrain from commenting on this due to the ongoing police investigation," head of the church's Japan chapter, Tomihiro Tanaka, said.
It is not known if she belongs to any other groups.
The press conference was limited to a select few journalists, prompting those locked outside to demand to be let in, saying it was a matter of national importance.
Mr Abe and his family had known links to the Unification Church, but the organisation has said he was never a member or an adviser.
In his statement to police, the shooter said he wanted to target leaders of the religious organisation, but that proved too difficult and ultimately it was former PM Abe who was easily accessible on a suburban street.
Experts say the motivations of Mr Abe's killer reveal long-held associations between Japan's conservative politicians and a series of new, small and sometimes fringe religious groups, the power those churches hold and how useful they are at garnering support and winning elections.
Religious groups in Japan
The Unification Church was founded in South Korea in 1954 by Sun Myung Moon, a self-declared messiah and strident anti-communist.
It has gained global media attention for its mass weddings where it marries thousands of couples at a time.
For its followers, the church offers a new interpretation of Christianity. Its detractors view it as a cult.
Yamagami's mother first joined the church around 1998, but stopped attending in a period between 2009 and 2017, a Unification Church official said.
About two to three years ago she re-established communication with church members, and in the last six months had been attending church events about once a month, they said.
Jeffrey Hall, an expert on Japanese politics and right-wing activism at Kanda University of International Studies, said some so-called "new religions" had a reputation for pressuring members into making donations.
"In the case of the Unification Church, there's definitely a very rich leadership group that benefits greatly from the donations of its members and a large group of members who are expected to donate money," he said.
"The idea that you can pay your way into salvation by donating more money."
He said exactly how much members are expected to donate was unclear, but exploitation of vulnerable families was likely to now be a focus for authorities.
"Definitely, you can expect more police attention to these kinds of groups in Japan now that this has been linked to the assassination of the most important politician in the country," Dr Hall said.
Shinzo Abe, Donald Trump spoke at church event
The link between Mr Abe and the Unification Church is no secret.
Last year, Mr Abe recorded a congratulatory video message that was played to the "Rally of Hope" summit organised by an NGO that is run by the Unification Church.
Mr Abe's speech followed that of another former world leader: Donald Trump.
"This seemed very strange for politicians to be sending congratulation videos to a church, which, if you look up its views, is hardly a mainstream Christian religion and seems quite bizarre to many people," Dr Hall said.
Dr Hall said conservative politicians have historically seen the Unification Church as a "useful ally" and Mr Abe's maternal grandfather, Nobusuke Kishi, was among those who originally sought the support of the group.
"Conservative Japanese politicians, particularly Abe's grandfather Kishi sought the support of Reverend Moon and his church in a sort of anti-communist alliance of civic and religious organisations," he said.
This was in the decades after World War II when smaller religions were flourishing and becoming involved in politics.
Other members of Mr Abe's faction of the Liberal Democratic Party (LDP) had known associations, and been known supporters, of the Unification Church.
"There is a video of prime minister [Takeo] Fukuda in the 1980s, giving a speech to the Unification Church where he's praising them. You can find quotations from former prime minister [Yasuhiro] Nakasone, congratulating people on the event of a mass wedding held in a stadium in 1992," Dr Hall said.
"This is a tradition that goes back for quite a while where they would get these voters to support them in elections and for events like these, it was seen as a prestigious thing for the church to receive a message from a politician that they could play on a big screen."
The associations between conservative politicians and religious groups in Japan serves a very clear purpose — it helps win elections.
Campaigning in Japan
Political campaigning in Japan is heavily regulated, with candidate signage limited to pre-determined spaces on billboards, and advertisements on television also heavily prohibited in the days before the election.
Large-scale political rallies are not allowed.
This forces candidates to hold many small, intimate rallies outside train stations, shopping centres and public squares.
It's common to find even high-profile candidates and politicians speaking to just a few dozen people standing on a milk crate.
Paul Nadeau, adjunct professor of political science at Temple University's Japan campus, said what Mr Abe was doing on the day he died "was completely normal in the realm of Japanese politics".
"It will be interesting to see how they decide to re-evaluate campaigning after this. Given how immediate the relationship has been between campaigners and the public, anything disrupting that would be a fundamental change," he said.
The ban on using the internet for political campaigning was only lifted in 2013, but it's a resource that still remains under-utilised.
James Brown, an academic from Tokyo's Temple University, said there might be some security changes for high-profile candidates in the wake of Mr Abe's assassination, but he did not expect the ruling LDP to drastically change the system that has "helped keep them in power for all but a few years since 1955".
"The current system is so entrenched that I don't expect any fundamental shift," he said.
"It also favours the LDP. They have an army of well-drilled supporters spread out throughout the country who have decades of experience in such campaigning."
Japan, unlike Australia, does not have compulsory voting.
The LDP's approval rating is only around 40 per cent, but a disjointed opposition and young voter disengagement have been significant forces behind their electoral domination.
Only 52 per cent of eligible voters cast a ballot for the recent upper house elections.
Using relatively small, but well-mobilised religious groups with a "committed" base has proven an effective way for the LDP to ensure support, Dr Hall said.
"You know they're going to show up to the polls," he said.
"They can be much more reliable than the average voter."
An 'embarrassing moment'
Dr Hall said Mr Abe's death has brought attention to connections between Japanese politicians and religious groups — something that has been a "taboo topic" in the country.
"It will be to — especially the conservative politicians in the LDP — a sort of embarrassing moment because probably a lot of them worked with these new religions hoping that it would never really be known by the wider voter base," Dr Hall said.
"For politicians who were involved with the Unification Church, and it wasn't just Abe for sure, it's going to be a painful experience for them."
The power of these groups though, is undeniable, and for a coalition that has again been elected to power, it is a formula that works.
Even if the role of religious groups in Japanese politics does change, Dr Hall believes it is a force "no major political party can ignore".
Mr Nadeau said another political response to this moment in Japan's history could be turning attention to the country's most vulnerable citizens.
"The idea that [Yamagami's] mother could be making excessive donations to this religious organisation would probably hit somebody like that a lot harder than someone who is more financially stable," he said.
"If you wanted to make a political program about this, I would turn the microscope to the precariat.
"Not that they're a threat, certainly not by any means, but that they need more attention. The insecurity and the instability in those lives is a lot more uncertain than we might have assumed."
