Kang Dojin was once the person who held the closest place in Yoo Seorin's heart. They had known each other since their college days and had once been each other's place to come home to, even though they never truly became a couple. Dojin was the first person who made Seorin feel she was worthy of being understood. But because of a decision he made in the past, their relationship ended without any real closure. Years later, Dojin reappeared in Seorin's life. He realized that the woman he once knew was still carrying the same wounds, perhaps even deeper ones. Now he lives with regret. Not just because he lost Seorin, but because he realized that when Seorin needed someone most, he was the one who chose to leave.

Kim Minji is Yoo Seorin’s best friend and the person who knows her best. They’ve been friends since high school and have continued to support each other into adulthood. Minji is the only person who knows almost every side of Yoo Seorin, including her bad habits, the wounds she hides, and the reason behind her cold demeanor. She never judges Seorin or forces her to change. To her, simply staying by her side matters more than giving advice. Even though she often worries about Seorin, Minji still respects the boundaries her friend has set. She believes that one day, Seorin will open her heart in her own way.

Lee Jiwon is an architect known for his calm, mature demeanor. He prefers listening over talking, and he always notices the little things others often overlook. To many people, Jiwon seems hard to approach because of his composed, serious nature. But beneath that, he is warm, empathetic, and always respects each person’s choices and boundaries. He met Yoo Seorin by chance, but the more often they crossed paths, the more he realized that she was hiding wounds far deeper than they appeared. Jiwon never forced Seorin to change. He never asked about her past. He simply chose to stay. To him, sometimes keeping someone company in silence means far more than a thousand words of comfort.

Park Hyerin is Yoo Seorin's coworker, with a cheerful, friendly personality and the kind of easygoing nature that lets her get along with anyone. Unlike Seorin, who prefers to keep to herself, Hyerin loves chatting, inviting people to eat together, and lightening the mood at the office. Though she's often seen as a little too friendly, Hyerin is actually very perceptive when it comes to other people's feelings. She can tell that Yoo Seorin isn't a proud woman who simply hates socializing, but someone carrying a burden no one else knows about. Hyerin has tried several times to get closer to Seorin, but she always respects the boundaries Seorin sets. She never forces Seorin to open up, only hoping that one day they can become friends who trust each other.