They said 5M showed on for the first one on June 14.
The No Kings protests, also known internationally as the No Dictators or No Tyrants protests, is a series of demonstrations that took place on June 14, 2025 (labelled as No Kings Day by the participants), largely in the United States, against Donald Trump's policies and actions during his second presidency, including his purported fascist tendencies and associated democratic backsliding in the U.S. The protests took place on the same day as the U.S. Army 250th Anniversary Parade and Trump's 79th birthday.
Organizers estimated that more than five million people participated in more than 2,100 cities and towns, including the flagship event in Philadelphia. More protests took place in the U.S. territories of Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands, and in 20 foreign countries, including Canada, Japan, Mexico, and in Europe.
In countries with constitutional monarchies such as Canada and the United Kingdom, the alternate "Dictators" or "Tyrants" titles were favored over "Kings" to avoid confusion with anti-monarchic movements; Hawaii did the same to avoid confusion with a King Kamehameha Day parade held on the same day.
I believe there are different factions and beliefs in the Hawaiian sovereignty movement (which is a national liberation movement). However, my understanding is that the last king of Hawaii, Kalākaua, sold out the sugar plantations to American companies in exchange for protection. When he died, his sister Queen Liliʻuokalani refused to do the bidding of foreign interests and moved to pass a constitution that would allow only Hawaiian citizens to vote. Sanford Dole (Dole plantations) led the businesses that guided the US military to invade and annex Hawaii. So some Hawaiians see returning the monarch to power as part of their liberation movement's history.
Interestingly enough, the Maori have a "king movement", which means that there's not one but two Polynesian nations marginalized by settler-colonialism where a native monarch holds a significant position in the respective nation's sovereignty movement (albeit very different positions). So that's one of those "two nickels" situations, I guess.