Seo Min-Jae, a reserved and thoughtful boy, and Kim Joon-Seo, a lively and charismatic extrovert, form an unlikely bond when they become childhood neighbors. Over the years, their connection deepens, but Min-Jae quietly develops feelings for Joon-Seo, who remains unaware while pursuing short-lived relationships. One day, after Joon-Seo goes through a breakup, Min-Jae comforts him, and in a moment of vulnerability, they share a kiss. However, the next day, things return to normal, leaving Min-Jae confused and uncertain about their relationship. Can love, fragile and uncertain like a paper plane, reach its destination against all odds?