He was still a powerful figure in .JP politics and was speaking at a campaign event when he was shot. He served something like 6 consecutive terms and only left office for health reasons, but he was still trying to push agendas through.

Other than that, who knows. I'm sure that various US politicians like Nixon and Reagan still have enemies even though they are both long since in the ground.

What was his agenda? Was it a controversial one?

Shinzo Abe was a far right nationalist racist and Japan War Crimes negationist. He inserted revisionist propaganda in history school manuals.

He was generally anti foreigners, anti equal rights.

He was a member of the crazy nationalist cult Nippon Kaigai that wants a return to the prewar status of the godly emperor and profess Japanese Yamato's pure race superiority. Look that up.

Wikipedia :

"Shinzo Abe [0] was affiliated with the openly ultranationalist organization Nippon Kaigi (Japan Conference). He was considered a right-wing populist and ultra-conservative within the LDP, and some media and books referred to him as a far-right politician. According to Professor Dominique Tasevski, his legacy can be defined by nationalism, historical revisionism, and a deterioration in Japan-South Korea relations."

"Nippon Kaigi [1] believes that "Japan should be applauded for liberating much of East Asia from Western colonial powers; that the 1946–1948 Tokyo War Crimes tribunals were illegitimate; and that killings by Imperial Japanese troops during the 1937 Nanjing Massacre were exaggerated or fabricated". The group vigorously defends Japan's claim in its territorial dispute over the Senkaku Islands with China, and denies that Japan forced the "comfort women" during World War II. Nippon Kaigi is opposed to feminism, LGBT rights, and the 1999 Gender Equality Law."

[0] https://en.wikipedia.org/wiki/Shinzo_Abe#Political_positions...

[1] https://en.wikipedia.org/wiki/Nippon_Kaigi#Objectives

He was still politically active, by publicly pushing his agenda, and by exerting his influence on other cabinet members as a senior leader of the ruling party.

His grandfather was a war criminal, and he has a track record of running interference for Japanese atrocities

my first guess is that it was a militarist gunman who was unhappy with not-enough-militarism from Abe, and, there must be a social group associated here, everything is social, including being a militarist. real information welcome

That's your justification for murder and assassination?

I think the parent is answering OP's question - which is about the _gunman_'s justification. The parent explaining behavior is not the same thing as the parent defending or justifying it.

Japan's stance of war crimes has been a point of tension between Japan and its East Asian neighbors.

These are matters of nationalism and affect forward looking geopolitical outcomes.

Following WWII, a tribunal was held in Tokyo along the lines of trying German war criminals. You can imagine how celebration of what others perceive to be German war criminals could lead to conflict.

Beyond the still active politician arguments: terrorism and revenge. Also the kind of people who do this thing often aren’t really driven by things most of us would call rational.

Adding to what others have said, there's also another key point, which is the elections that are coming up (2 days unless this gets delayed?).

This event can be used in multitude of forms for a multitude of results by a multitude of people.

> What motivation is there to kill an ex prime minister?

Apparently he was "dissatisfied" with Abe and wanted to kill him.

"Earlier, it was reported that the suspect decided to kill Abe because he disagreed with his policies.

According to the NHK, the police now say that Yamagami told investigators he had a grudge against Abe and decided to kill him."

https://www.jantakareporter.com/entertainment/who-is-shinzo-...

Still a powerful political figure. Comes from a very influential political family - grandfather and father were both politicians. His brother is the current minister of defense.

He's still a powerful political figure. He even might have chance to become a candidate or influencing the decision on who gonna be candidate from his party.