However, parents have only recently begun to address the issue after a series of media reports focused attention on it.
Featuring top stars Zhou Dongyu and Yiyang Qianxi (also known as Jackson Yee), the movie tells the story of a high school student who is harassed on campus and later becomes caught up in a murder.
It contains several scenes of violent bullying and bloodshed.
Adapted from the novel Young and Beautiful by Jiu Yuexi, it proved an instant commercial success after opening in theaters on Friday.
This was less than a week after lawmakers looked to legislate against bullying and threats, both online and offline, in the Minors Protection Law, aimed at those under 18.
Although a constant theme for Japanese and South Korean films, school bullying has been largely ignored by mainland moviemakers.
In recent years, the public has been shocked and angered by online video clips showing schoolchildren being assaulted, humiliated and verbally abused by groups of youngsters in classrooms, backstreet alleys and even bathrooms, to evade teachers' attention.
Such clips are usually removed from Sina Weibo and other social media platforms, for fear of inciting copycat incidents or secondary injuries being inflicted.
One video that circulated recently involved a 16-year-old schoolgirl in Jiangsu province who was slapped in the face and forced to kowtow following a row while switching seats in a classroom. The incident was recorded by those responsible and shared online in an apparent attempt to humiliate the victim.
In 2015, a report by China Central Television focused on the distress and trauma experienced by students who had been bullied.
It told the story of a 14-year-old student from Shandong province who jumped from the fourth floor after several classmates repeatedly prevented him from using the bathroom. The student severely injured his back and legs.
Many viewers told of their frustration, as the perpetrators in many cases go unpunished, partly due to those who are younger than 14 being below the age of criminal responsibility.
One Sina Weibo user commented that the indifference of parents, teachers and bystanders had contributed to problem of school violence, and that the consequences have been widespread in recent years, with more problematic children having internet access.
Although the media and lawmakers have begun to focus attention on the issue, school violence has been a problem long before the arrival of social media platforms.
I was unaware at the time that such acts placed me in the ranks of school bullies, albeit to a less-serious degree, Li, 28, said.
He added that school violence had long been understated by parents and teachers, until brutal video clips circulated online revealed how serious the problem had become.
Fast-expanding internet access among minors, along with the rise of loosely-controlled social media and video-streaming services, have exposed young people to violent and sexual content. According to children's law researcher Yuan Ningning, such content is strongly linked to juvenile offences, especially among children with no effective supervision from parents or guardians.
Some data showed that over 70 percent of underage offenders had access to improper information via the internet, Yuan said.
According to a recent report by the Central Committee of the Chinese Communist Youth League and the China Internet Network Information Center, about one-third of netizens under age 18 reported encountering pornography, violence and illegal drug use while surfing the internet.
Sun Hongyan, a researcher at the China Youth and Children Research Center, said the percentage was even higher when internet censorship had not been so rigorously enforced.
Citing figures from a report by the center in 2009, she said 48.3 percent of adolescents had visited porn sites, and 43.4 percent had received emails that suggested violence, or in which they were bullied.
Figures from the China Internet Network Information Center show that by the end of 2015, there were more than 79 million teenagers in rural areas with internet access.
With the parents of many working in better-paying jobs in big cities, the teenagers were under the limited guardianship of other relatives, thus becoming more vulnerable to improper use of the internet.
Although easier internet access has made it easier for young bullies to prey on victims, it has also created a backlash by fueling a gradual shift in attitude toward juvenile offences, prompting policymakers to act.
Top prosecutors have stepped up efforts to bring school bullies to justice.
Figures released by the Supreme People's Procuratorate in May show that since last year it approved the detention of 3,407 students involved in campus bullying, and pressed charges against 5,750.
Some 17,300 prosecutors have been named deputy principals at primary and secondary schools nationwide to oversee legal affairs on campus, and to deter offences, the procuratorate said.
Top lawmakers focused on the issue when they gathered in Beijing for a bimonthly meeting this month.
In a draft revision of the Minors Protection Law that had been submitted to the top legislature for the first review, lawmakers defined school bullying as single or repeated incidents, along with humiliation on and off campus that led to physical, financial or psychological losses.
The definition also applies to such incidents taking place online.
The lawmakers also sought to make it compulsory for school authorities to hold lectures and consultations aimed at preventing bullying, and for traumatized students to recover.
Under the draft, schools must notify guardians in such cases, and punish or educate offenders in cooperation with the authorities.
The draft also prohibits threats, insults and attacks on minors in written, visual or audio form and empowers parents and guardians to demand that internet service providers remove indecent content.
At the meeting, Li Fei, a member of the National People's Congress Standing Committee, noted a link between school violence and misleading online games. He said the problem was becoming increasingly hard to ignore, as portable devices made these games easily accessible.
Many bullies imitate acts in these games, with corresponding consequences, he said. It is shear imitation.
Liu Xiya, a deputy to the National People's Congress, suggested that parents and guardians be held accountable if their children are involved in bullying.
We've seen many cases in which parents of school bullies have attempted to shirk their responsibility, she said.