Stray Kids' Hyunjin was impressed by 2PM's Junho.

On the 31st, a video titled 'SKZ-TALKER' was uploaded to Stray Kids' official YouTube channel.

On this day, a behind-the-scenes video of Stray Kids' Hyunjin and Junho filming the new song 'ChkChkBoom' challenge was revealed. After seeing Hyunjin's demonstration, Junho exclaimed, "You're good." Junho said, "How do you learn and film so quickly these days? That means it'll take me a while," and asked Hyunjin to show him the moves again.

Junho tried to learn each and every move carefully and kept practicing. After seeing this, Hyunjin said, "Can you believe it? Junho hyung, who works so hard on our song. I'm touched."

Lee Junho suggested, "Why don't we get together and do something at the end of the challenge video?" Hyunjin said, "Do you want to do it together?" and added, "Don't be surprised if we put our arms around each other at the end." Lee Junho asked for lighting so that Hyunjin could look good, and they excitedly filmed the challenge video.

Hyunjin, who put her arm around Lee Junho's arm, felt embarrassed and said, "I'm an introvert too," and they re-filmed the challenge video to make it more natural. Hyunjin told Lee Junho, "It's definitely much cooler when you relax. I love it."

After filming the challenge with Lee Junho, Hyunjin said, "I was touched because you worked so hard. Even when I become that senior, I want to work hard for my juniors."