”I wanted to see the reaction”... Bomb teaser at Shinsegae Department Store blamed on ”juvenile delinquents” = South Korea

The perpetrator who threatened to blow up the main branch of Shinsegae Department Store in Jung-gu, Seoul, has been identified as a junior high school student who is considered a juvenile delinquent.
According to police on the 6th, the Jeju West Police Station is investigating a first-year middle school student, A, on suspicion of public intimidation.
Police tracked down the IP address and arrested A at his home in Jeju City around 7 pm on the 5th. A is a juvenile delinquent (aged 10 or over, 1 year old) who is subject to protective measures instead of criminal punishment.
During the police investigation, A stated, "I wanted to see how people would react if I posted a teaser about the explosion of (Shinsekai Department Store)." A was born with severe autism spectrum disorder.
Prior to this, at around 12:36 pm on the 5th, an explosive device was posted on the online community "DC Inside Composite Gallery" under the title "Shinsegae Department Store Explosion Guide."
The poster posted a message claiming that a bomb had been set up and alluding to a terrorist attack. The poster said, "You should never go to the main Shinsegae Department Store (in Seoul) today," and added, "I was the one who was involved in the bombing yesterday."
"I've placed drugs on the first floor. I'll detonate it at 3pm today," he wrote. The post has now been deleted. Police received the call about an hour later, at around 1:43pm, and a department store employee and customer
After evacuating about 4,000 customers, the department store was searched but no explosives were found.