Japan has marked a year since the shock assassination of former prime minister Shinzo Abe, the country's longest-serving leader and a towering political figure.

On Saturday, visitors from all walks of life formed a long queue outside Tokyo's Zojoji Buddhist temple, offering flowers before framed pictures of a smiling Abe.

"I think he was the icon of Japanese people. He was the icon of the conservatives," said mourner Tomoko Shimoda, 57.

She said "the way he communicated with other people, what he said publicly, and the way he behaved" made a lasting impression on her.

Hiroyuki Kumagi, 69, said he was "a real worshipper of Mr. Abe".

"I participated in the prayer at the last year's national funeral, and of course I am here today," he said.

In the western Nara region, people brought flowers and prayed outside Yamato-Saidaiji Station -the site of Abe's shooting.

Abe was gunned down in broad daylight while giving a campaign speech in western Japan, targeted by a man allegedly angry over the former leader's links to the Unification Church.

The suspect, Tetsuya Yamagami, was apprehended on the spot and is said to have resented the sect over large donations that his mother made that bankrupted his family.

His death prompted a flood of condolences from international leaders, many of whom met the former prime minister as he worked to raise Japan's diplomatic profile. But at home, the assassination caused waves of political upheaval.

First, the renewed attention on the Unification Church -whose members are sometimes called "Moonies" - prompted revelations of deep ties between Japan's conservative lawmakers and the sect.

Prime Minister Fumio Kishida was forced to first investigate the ties and then announce his party would sever any relations with the church.

Abe's murder also prompted soul-searching over Japan's security arrangements, with pledges to improve the protection of politicians.