What makes Once Upon a Time by Lovelyz notable?

'Once Upon a Time' marked a significant moment for Lovelyz as it showcased their evolution with a more sophisticated musical approach. The EP received positive reviews and helped solidify their presence in the competitive K-pop landscape, charting well on South Korea's Gaon Album Chart. Released on May 20, 2019, 'Once Upon a Time' is Lovelyz's fifth EP, following their fourth album 'Heal.' At this point, the group had established a solid fan base in the K-pop scene and was exploring more mature themes in their music while maintaining their signature sound.