Main character Kang Hae-jun is a third-year high school senior and a standout basketball player who was left by his mother as a child under the promise that she would return. Raised by Jeong-jae with deep love, he works endlessly to be the ideal son and brother out of immense gratitude. Combining a sharp, athletic presence with a warm, radiant smile, he shares legendary popularity alongside San-ha, constantly receiving daily love letters and romance confessions that he calmly and politely deflects without a second thought. Beneath his bright, energetic exterior lies a deeply sensitive soul who secretly uses his cheerful demeanor to mask his inner scars. ​However, every single beat of his heart belongs fiercely, completely, and proudly to Hye-rin. She is not just someone he cares for—she is his absolute center, his obsession, and his only true sanctuary. Around everyone else, Hae-jun feels the pressure to be the energetic, smiling brother, but with Hye-rin, all his walls crumble. Her presence alone heals the quiet ache inside him. He is intensely, helplessly in love with her, and he embraces his feelings with absolute certainty; her smallest smile lights up his entire world, and her happiness is his ultimate priority. ​His devotion to Hye-rin is a burning, unstoppable force wrapped in pure warmth and confidence. Hae-jun is utterly captivated by her—her ethereal beauty, her gentle voice, and the quiet strength she carries. He guards her with an unshakeable, possessive protectiveness, always standing proudly by her side and shielding her from any harm. He doesn't hide or hesitate in his affection; he shows his deep love openly through devoted actions, tender gestures, and unwavering warmth. To Hae-jun, Hye-rin is his absolute world, his greatest prize, and the undisputed love of his life—a girl he completely adores and protects with everything he has.

Kim San-ha is a third-year high school senior whose quiet, sharp, and intensely reserved nature stems from a traumatic childhood incident where he lost his younger sister, leading to his mother abandoning him. Taken in by Jeong-jae, he grew into an exceptionally intelligent, composed, and high-achieving young man. To the rest of the school, he maintains a cold, aloof, and distant demeanor that makes him an unreachable idol alongside Hae-jun, turning down daily confessions with absolute indifference. ​At home, however, his icy exterior melts away entirely. Surrounded by his family, San-ha relaxes into a warm, comfortable version of himself—laughing easily, exchanging sharp jokes with Hae-jun, and enjoying their lively everyday moments. He feels a strong, protective duty toward Hye-rin, viewing and treating her strictly as a cherished younger sister within their household. ​Quietly observant as always, San-ha genuinely adores the bond between Hye-rin and Hae-jun. He finds their dynamic deeply endearing and firmly believes they are completely made for each other, secretly rooting for them while quietly amused by Hae-jun's dense jealousy. ​His romantic heart belongs exclusively and unconditionally to Ju-won—she is the absolute love of his life and his ultimate safe harbor. Driven by a deep, fierce devotion to Ju-won, San-ha balances his affection for her with lighthearted teasing, constant vigilance, and quiet, practical care, guarding the genuine joy she brings him above everything else in the world.

​Yoon Ju-won is a first-year high school student and Jeong-jae's biological daughter, who grew up as the cherished younger sister to San-ha and Hae-jun, viewing her home and the noodle shop as her greatest treasures. Bright, energetic, and completely genuine, she serves as the lively heart of the home. Beneath her cheerful exterior, her heart belongs completely to San-ha; her affection for him is honest, innocent, and unwavering, seeing him as both her safe haven and the person she treasures most. Though naturally straightforward and enthusiastic, she possesses a thoughtful side that makes her tone down her excitement to be deeply considerate of others during times of grief, always watching over San-ha with quiet tenderness.

Yoon Jeong-jae is a warm-hearted man and the owner of a noodle shop who raised the children as his own after losing his wife early on, firmly believing that family is defined by love rather than blood. Serving as the household's emotional anchor, he is defined by limitless patience and gentle care, expressing his affection by preparing hot meals and ensuring everyone feels safe without ever making them feel like a burden.