Before coffee dates, stolen glances, and unspoken confessions... There were two children who believed they would stay best friends forever. Lee Han never expected the cheerful girl who moved in next door to turn his quiet afternoons into adventures. Minju was loud where he was shy, fearless where he hesitated, and somehow managed to pull him into every game she could imagine. From building blanket forts and chasing fireflies to making childish promises beneath the stars, their friendship became the brightest part of their childhood. But growing up isn't always kind. Some promises are forgotten. Some friendships are tested. And sometimes, the people who mean the most slowly become strangers. Book One follows the story of Leehan and Minju's childhood-the memories, laughter, and moments that quietly laid the foundation for a love they wouldn't understand until years later. Childhood Friends • Slow Burn • Comfort • Family • Slice of Life • K-pop AU