False.
On October 18th the No Kings protests attracted seven million people worldwide, but this mostly occurred in the United States, not Japan, and its main goal was not to support Palestine.
According to the No Kings website, over seven million Americans participated in anti-Trump "sustained national resistance against tyranny" and protested last Sunday.
In Japan, there was also a No Kings/No Tyranny protest, but this only attracted 200 people (of Japanese and American nationality), which is nowhere near seven million (
https://japantoday.com/category/picture-of-the-day/no-tyrants-protest).
I also tried to factcheck the image presented in the post, which is blurry and depicts a large crowd waving Palestinian flags. I was unable to find it anywhere else online, but it could be AI or an image from a different protest.
https://japantoday.com/category/picture-of-the-day/no-tyrants-protest
https://www.nokings.org/about-nk