Did the Kishida administration deploy nuclear weapons in Japan? No, that's not true: There is no such evidence.
The claim reappeared as a video (archived here) posted on TikTok on September 15th, 2022, in which Tomoko Horaguchi, an assemblywoman from Tokyo Suginami claimed that the Kishida administration is deploying nuclear weapons. It opened (translated to English by Lead Stories staff):
The policy proposed by the Kishida administration includes deploying nuclear missiles.
This is what the post looked like on TikTok at the time of writing:
(Source: TikTok screenshot taken on Tue Apr 18 14:19:52 2023 UTC)
In this video, you can see Horaguchi debating with a number of panelists. The original video is from ABEMAPrime aired on September 8th, 2022.
Here, you can see one of the panelists saying:
It is said that the Self-Defense Forces will be dispatched to the Nansei Islands. But the nuclear missile deployment...What you're saying is quite a leap!
After this debate, Horaguchi posted on her website about the claim and summarized the points and views that she could not explain, but there was no evidence to prove her point.
Why were they even discussing this? This discussion was about the Kishida administration's National Security and the National Defense Strategy.
Here is what did happen, according to a January 31st, 2023 article on Yomiuri:
On December 16, 2022, the government approved the "three security documents" of the new National Security Strategy, the National Defense Strategy (former National Defense Program Guidelines), and the Defense Buildup Plan (former Mid-Term Defense Plan). Decided to possess "counterattack ability" to destroy the launch base.
The most updated plan of the Japanese Ministry of Defense is summarized in an April 11th, 2023 article:
The Ministry of Defense announced on the 11th that it plans to develop a long-range missile that can be launched from submarines of the Maritime Self-Defense Force.
In terms of counterattack capabilities, Japan will also acquire the US-made Tomahawk cruise missile. Four hundred of them will be purchased and installed on MSDF Aegis destroyers.
None of these announcements show that Japan has nuclear weapons, nor that it is deploying nuclear weapons. According to Nuclear Threat Initiative, a non-partisan and non-profit global security organization, Japan adheres to non-nuclear principles, meaning that the country "shall not possess, produce, or base nuclear weapons."