(Kyodo) Police guarded streets, parks and other potential protest hot spots in Shanghai and Beijing on Sunday to head off any further anti-Japan protests after demonstrations last month led to vandalism and a diplomatic rift.
In Beijing, about 200 police officers stood guard at the Hailong Building, a starting point for the April 9 protests that drew upward of 10,000 people and culminated in vandalism to Japanese diplomatic property as well as three Japanese-style restaurants.
About 1,000 Shanghai police officers weathered a downpour to guard the Japanese Consulate, where on April 16 windows were broken with rocks and other projectiles by some of the 20,000 demonstrators who marched there.
I think there may well be protests on May 4th anyway.
This 4th May is the 86th anniversary of the original May 4th Movement, when
"over 3000 students of Peking University and other schools gathered together in front of Tiananmen and held a demonstration. They shouted out such slogans as "Struggle for the sovereignty externally, get rid of the national traitors at home", "Do away with the 'Twenty-One Demands'" [of the Japanese government], "Don't sign the Versailles Treaty". They demanded with one voice to punish such figures as Cao Rulin, Zhang Zongxiang, and Lu Zongyu, who held important posts as diplomats. The enraged students even burnt Cao Rulin's house. The government of the Northern Warlords suppressed the demonstration and arrested many students. ...
"The May Fourth Movement marked the beginning of the New Democratic Revolution in China. It also served as a intellectual turning point in China. It was the seminal event that radicalized Chinese intellectual thought. Previously Western style liberal democracy had a degree of traction amongst Chinese intellectuals. However the Versailles Treaty was viewed as a betrayal." [because of the concessions offered to Japanese imperialism] (from Wikipedia).