A Manhattan high schooler was bullied and beaten up by two other students – including one brandishing a Taser – and the administration failed to act despite being aware of prior threats, a new lawsuit alleges.

Jihya Brown, 15, and her grandmother Denise Tucker filed suit against the city Department of Education last week over the May 26 incident that left the then-10th grader with a “fractured nose, bruising and swelling of her face [and] hair loss,” according to the court papers.

The teen and her grandmother claim officials at the Urban Assembly Academy of Government and Law in the Lower East Side failed to act after Brown was first threatened with a Taser by the student who later attacked her.

“If someone would have taken it seriously the first time this wouldn’t have happened to my granddaughter,” Tucker told The Post. “No one did anything.”

The teen says a 9th grader at the school — identified in court papers as ZNL — threatened her with a Taser for the first time on March 3 after the pair bumped into each other in the hallway.

“It started off with her bumping me and then screaming in the hallway saying I bumped her,” she told The Post. “She waved the Taser and attempted to tase me with it.”

The teen alerted the principal — but the school failed to report the scary incident to the police, intervene or punish the student in any way, according to the Manhattan Supreme Court lawsuit from Wednesday.

“She is trying to attack me for no reason. I don’t want to fight. I don’t know her,” Brown said she told the principal, adding that she was crying at the time.

Then, on May 26, Brown claims the same student threatened her again while she was sitting in class, “saying how she is going to beat me up, she is going to F me up, she is going to punch me, and there was nothing I could do about it,” she recalled.

Brown says she went to her school counselor before going home that day and reported the threats and how she felt unsafe.

“I went to her for my safety to be reassured,” the teen said, adding that the counselor’s response was: “Don’t worry about it. Calm down. Leave it alone and go home.”

“I was petrified,” Brown said. “I was stressed, hurt and my life was in jeopardy. She swept it under the rug.

“And on my way home I was followed and assaulted.”

The teen says ZNL followed her as she headed to a subway station where she was set to meet her grandmother and again waved around the Taser, threatening to use it before Brown’s pal cut in and said “I’m not going to let you Tase my friend.”

But then ZNL’s friend – identified in court papers as NG – allegedly attacked Brown, repeatedly punching her in the face, pulling out her hair and dragging her on the ground, she said.

It took the teen more than six weeks to recover, she said.

In addition to the physical injuries, she also suffered, “fear, fright, shock, humiliation and emotional distress,” the suit says.

Brown said the incident was humiliating and embarrassing.

“I don’t know these girls, I don’t say anything to them and for no reason my life was put in jeopardy,” Brown said.

“I have to be insulted, I have to be beaten, I have to have bruises and burns on my body from being dragged on the concrete,” Brown said. “My hair has to be pulled out, my face has to be battered … in front of everybody on the street.”

Her grandmother said she was waiting for Brown at the train station when she saw her arrive with blood on her face and clothes.

“I was so upset, so hurt,” Tucker said.

The students, parents and administration officials met over Zoom where the school decided not to take action against the assailants – instead merely warning that if it happened again there would be consequences, Brown said.

“My safety wasn’t prioritized,” Brown said of the school’s inaction afterwards. “Now you are going to tell me the next time there would be consequences?”

Brown – who is now in 11th grade – finished the school year remotely and transferred to a public school in Brooklyn where she is now, she said.

“The first couple days I cried,” Brown said of starting at the new school “I also felt isolated … I was by myself.”

Her suit is seeking unspecified damages from the DOE and from the two students.

“I think it’s outrageous that the school looked the other way and tried to protect this other child,” Brown’s lawyer Michael H. Joseph told The Post. “They are fostering criminals by not calling the police when incidents like this occur.”

Joseph added: “The lawsuit is the only way to make them take their students’ safety seriously.”

DOE spokesperson Arthur Nevins said the agency will review the lawsuit.

“Any allegations of threatening and bullying behavior at school are of utmost concern and the safety of our students is our absolute top priority,” Nevins said.

A spokesperson with the city Law Department said it would review the suit and respond in the litigation.

Additional reporting by Cayla Bamberger