In 2017, a 16-year-old Korean girl killed an elementary school student in Incheon

On March 29, 2017, Kim abducted and murdered A Yang, a second grader at an elementary school in Dongchun-dong, Yeonsu-gu, Incheon. The case is also known as the "Remin Case" after Kim's Twitter handle. Kim and her accomplice, Park Mo, 20, met through a self-portrait community on Twitter two months before the incident. During the police investigation, Kim was found to have searched for the words "murder" and "crazy" on his computer before the crime. 

"He was obsessed with murder and crazy things in the media, so it's likely that he committed the crime to fulfill those desires," said Kim Kyung-ho, head of the criminal investigation division at Yeonsu Police Station. "The dramas and novels he watched included scenes of desecrating corpses or cleaning up the scene." According to witnesses, Kim had been regularly watching children at a nearby park prior to the incident.

On the afternoon of March 29, 2017, while at the playground, Kim used his smartphone to look up the school's closing times and weekly schedule. Ms. A, a second-grade girl who was playing with two friends, asked Kim to borrow her phone to call her parents. 

Ms. Kim lured A to her home by telling her that her phone had no battery and that she should use her home phone. It was later revealed that Ms. Kim's phone had plenty of battery and that she had lied to lure A to her home. Ms. A's two friends left with the religious people for a while and later returned to the park.

Kim's apartment was on the 15th floor, but she got off at the 13th floor and walked up two flights of stairs because she was worried about CCTV. At around 3pm, Kim lured Ms. A to her room to play with her cat and then murdered her. During the course of the crime, Kim exchanged messages with Park, including "I got you," "You're alive, kid," and "I put a wire around your neck," to which Park responded with advice about the crime, including "Have you checked the CCTV?" and "You have beautiful fingers," to which Kim replied that she had.

Kim then dragged Ms. A's body to the bathroom, dismembered and mutilated her body, and cleaned the bathroom. Kim Yang placed the dismembered body parts in a garbage bag and disposed of them in the apartment complex's garbage disposal. To confuse the CCTV investigation, Kim Yang also disguised himself in clothes that were completely different from the clothes he wore when he entered the apartment.

He then made his way to the rooftop water tank of his apartment complex, where he climbed a ladder and left what was left of Ms. A's body there. When police later investigated the house, they found a blood-stained weapon by detecting luminescence throughout the bathroom. All of this happened within three hours. 

According to police reports, no one was home at the time of the incident, including Kim Yang's parents - this was a lone act. Kim Yang cut off part of Ms. A's finger and put it in a bag. At 4:09 p.m., he left the house and took the subway to Seoul at 4:30 p.m. 

He then met Park Yang at 5:44 p.m. and handed him the bag containing the body. Park Yang reportedly carried the bag for about three hours until about 8:30 p.m., eating and carrying the body calmly. Park was still carrying the bag when she returned to the subway station near her home at 9:47 p.m. She claimed to have thrown it away because she was scared of the gift she received on her way home.

When she didn't return, her family naturally went looking for her. They found the bag she had left at the playground and thought, "Maybe she went to a friend's house or took a nap," never imagining the horrific ending that awaited them. Neither did the residents of the apartment. 

However, after scrutinizing the CCTV footage, they found the child coming down from the elevator, showed a photo of the suspect (Kim Yang), and went door to door searching through closets and other areas of the house. This was broadcast live on the residents' chat room. 

The morning after the grim truth was revealed, some shocked residents even made comparisons to the Sewol ferry disaster (because so many people witnessed the events unfold in real time). It wasn't until after 10 p.m. that night that the victim's body was found. 

The father was the first to identify the body, and the mother later testified in court that "when I saw him crying when he came back, I realized that I would never see my child again." Then, police noticed something suspicious at Kim's house and arrested her after she returned home from a meeting with Park, who had received a "wanted" call from the police. Kim was arrested after midnight.

The investigation revealed that Ms. A's body had been left on the roof of the building after climbing the ladder seen in the photo. Ms. A's parents reported her missing to the police at around 4 p.m. The police conducted an investigation, secured CCTV footage of Ms. Kim and Ms. A riding the elevator together, and searched the apartment complex. 

They found Mr. A's body on the roof of the apartment and arrested Kim Yang shortly thereafter. An autopsy revealed that Mr. A had been strangled, and Kim Yang confessed to committing the murder using a tablet PC charging cable. On April 10, his alleged accomplice, Park Yang, was also detained for aiding and abetting the murder.

On April 6, 2017, the Yeonsu Police Station in Incheon detained Kim Yang, a high school dropout, for luring and killing a minor with drugs and for mutilating and abandoning the body. Detective Kim stated that Kim's motive for the crime was unclear as she gave conflicting statements, such as "I don't remember" and "Miss A killed her cat and I retaliated."

Experts interviewed by the TV program "I Want to Know" stated that Kim's calculated actions, such as wearing disguises and cleaning up the crime scene, suggested that the murders were premeditated and not the result of schizophrenic impulses. Kim Yang even claimed to have multiple personalities and blamed others for the murders, a defense often used by the mentally ill to avoid punishment.

On April 11, 2017, an arrest warrant was issued for an accomplice, Park Yang, who allegedly took delivery of the mutilated body parts and dumped them. Police investigating Kim's whereabouts after the crime uncovered Park's involvement. Although Park Yang denied the allegations, police used CCTV analysis and phone records to determine culpability. On May 19, 2017, prosecutors charged Kim Yang with violating the Specified Crimes Act, including drugging and commercial solicitation, and Park Yang with aiding and abetting murder and abandoning a corpse on May 8, 2017.

Kim Yang, the main perpetrator, was only indicted on May 19, 2017, after undergoing a psychiatric evaluation so that his prosecutors would not inflame public sentiment. On June 14, 2018, Park Yang filed an application for a stay of execution with the Supreme Court. The court assigned the case to a three-judge panel presided over by Justice Cho Hee-dae on June 22, 2018. 

On September 13, 2018, the Supreme Court affirmed the trial court's ruling, sentencing Kim, who was named as the main perpetrator, to 20 years in prison and Park, who was charged as an accomplice, to 13 years in prison. Both were ordered to wear electronic ankle bracelets.