'The Unit's UNB made their entrance on the March 17 installment of 'Immortal Song'.

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For the special dedicated to composer Jang Kyung Soo, UNB covered Yoo Mi Ri's 1987 hit "Note of Youth". The idol group retained the '80s dance vibe, but they also did their own modern take on the song with added choreography.

UNB were asked about their teamwork considering the members have come together from different groups, and they responded, "We can't help but have good teamwork because we've seen each other struggle through a survival show," referring to their experience on 'The Unit'. Former mentor Hwang Chi Yeol also commented, "I feel happy seeing that they've improved since their time on 'The Unit'."