At the height of the Japanese university protests, protesters occupied Shinjuku Station in Tokyo and clashed violently with police.

In 1968 and 1969, student protests at several Japanese universities ultimately forced the closure of campuses across Japan. Known as daigaku funsō or daigaku tōsō, the protests were part of the worldwide protest cycle in 1968 and the late-1960s Japanese protest cycle, including the Anpo protests of 1970 and the struggle against the construction of Narita Airport. Students demonstrated initially against practical issues in universities and eventually formed the Zenkyōtō in mid-1968 to organize themselves. The Act on Temporary Measures concerning University Management allowed for the dispersal of protesters in 1969.

Shinjuku Station is a major railway station in Tokyo, Japan, that serves as the main connecting hub for rail traffic between central/eastern Tokyo and Western Tokyo on the inter-city rail, commuter rail, and subway lines. The station straddles the boundary between the Shinjuku and Shibuya special wards. In Shinjuku, it is in the Nishi-Shinjuku and Shinjuku districts; in Shibuya, it is in the Yoyogi and Sendagaya districts.

Tokyo, officially the Tokyo Metropolis, is the capital and most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is one of the most populous urban areas in the world. The Greater Tokyo Area, which includes Tokyo and parts of six neighboring prefectures, is the most populous metropolitan area in the world, with 41 million residents as of 2024.

The Shinjuku riot was a violent clash between police and anti-Vietnam War protesters who occupied Shinjuku Station in Tokyo, Japan, on 21 October 1968. The incident took place in the context of mass demonstrations in observation of "International Anti-War Day". In total more than 800,000 Japanese left-wing activists, including the Beheiren anti-war coalition, labor unionists, and radical student groups also participating in the 1968–1969 Japanese university protests, carried out a variety of demonstrations and protest activities across Japan. By occupying Shinjuku Station and disrupting the normal transit of trains, a large group of protesters in Tokyo hoped to express their disapproval of the Japanese government's support for the United States-led war in Vietnam. The riot was mostly broken up by the morning of 22 October due to the invocation of the Anti-Riot Law by police, an act that was largely condoned by the press and led to greater police confidence.