On January 12, 2025, SM Entertainment made headlines by introducing its newest 25-member male trainee group, SMTR25, at the SMTOWN Live 2025 concert. The event, held at the Gocheok Sky Dome in ...

JJ was previously featured in HYBE's 2021 YouTube series Trainee A. After his potential debut under HYBE fell through, he reportedly joined SM Entertainment, though SM has never commented on this.