The National Police Agency had approved the security plan for the weekend rally in Wakayama, Chief Cabinet Secretary Hirokazu Matsuno said on Monday.
The government has instructed authorities to strengthen security measures and to ensure safety precautions at gatherings of VIPs, he added.
Kishida is among government officials who acknowledged flaws in security when Abe was gunned down last July.
In Saturday’s attack, the suspect was about 10m from Kishida, according to media reports.
The premier was being served a speciality seafood dish just before the attack, media reported, and news videos showed Kishida looking toward an outdoor parking area, with the crowd behind him in a roofed enclosure.
In one video, a smoking canister lands and rolls toward Kishida as shouts fill the air. A security agent blocks the device with a bulletproof briefcase kicks it away, as he and other security men crowd around Kishida and push him toward a parking area.
“EXTREMELY DANGEROUS”
After the device was thrown, a bystander grabbed a young man in a headlock, while someone who appeared to be another member of the public grabbed the suspect around the waist as police swarmed and dragged him to the ground, videos showed.
“There’s no doubt this was an extremely dangerous incident,” said Katsuhiko Ikeda, former superintendent general of the Tokyo police.
He said it showed that a review of security plans by the National Police Agency could only go so far.
“A big factor is whether the forces on the ground can make the correct decision in every eventuality, and have the proper sense of crisis,” he said.
Isao Itabashi, chief analyst at the Council for Public Policy Chief, said public appearances by top politicians should be indoors, with bag checks and metal detectors in place.
“The biggest issue here was that an explosive device made its way in,” he said. “The lessons from Abe’s incident haven’t been applied.”
Initial reports called the blast a smoke bomb, but investigations and a search of the suspect’s home indicated he had material to make pipe bombs, media reported.
One bystander, a fisherman, said the blast had injured his back, the Asahi newspaper reported. Part of the explosive device was found on a roof, 40m from where it went off, public broadcaster NHK reported.