Heejin's debut with 'Vivid' was such a pivotal moment in LOONA's pre-debut project! I still get goosebumps thinking about how fresh and bold her solo debut felt. Back in 2016, LOONA was just this mysterious concept—no one knew much about them, but then Heejin dropped 'Vivid' like a bombshell. The song was this vibrant mix of pop and funk, totally showcasing her charisma. The music video was colorful and playful, matching her energy perfectly. What stood out to me was how she carried the entire thing alone—no other members, just her owning the stage. It set the tone for LOONA's whole 'each member gets a solo' concept, which was genius. I remember rewatching the MV for days, trying to catch all the little hints about the LOONA universe. Even now, 'Vivid' feels like a love letter to Heejin's star power.
And let's not forget the b-side, 'ViViD' (acoustic version), which showed her softer side. It was wild seeing one artist deliver two such different vibes right off the bat. The way BBC built hype around her—mystery teasers, then this explosive debut—was masterful. Heejin wasn't just introducing herself; she was introducing LOONA's entire aesthetic. No wonder she's often called the 'first piece' of the puzzle. Her debut still holds up as one of the most memorable solo debuts in K-pop for me.