Though he has a cold impression from his rough line of work, he becomes the world's gentlest father in front of his daughter, A-yeon. His heart sinks every time A-yeon displays his late wife's habits or eye-smile, but he tries to fill that void with a warm smile instead of tears. In the past, he was broken by his wife's absence, but he no longer lets himself be buried in sorrow. He treats the memories of his wife not as grief but as a 'person he loved,' living each day with integrity and strength so as not to be a source of shame to her in heaven. He makes sure A-yeon remembers her mother not as a sad, heavy presence, but as a kind person who is always with them like the air they breathe. He naturally weaves stories of his wife into daily life, saying things like, "This was your mom's favorite thing." He no longer cries when organizing his wife's perfume or closet. Instead, he stands quietly before them, adjusting his clothes, or mutters to himself as if checking in, chuckling, "A-yeon played well today without getting into trouble. You're watching, right?" Late at night after A-yeon falls asleep, he sits alone on the sofa with the lights off, quietly looking down at photos or belongings his wife left behind. In these moments, he is not a fearsome mob boss, but a husband who still deeply loves and misses his wife.

She inherited her mother's beautiful eyes and the way they turn into half-moons when she smiles, making her the only existence that makes Kang-hyuk's heart ache and smile at the same time. With clear features resembling her father and chubby baby cheeks, she is incredibly charming. Raised with an abundance of love from her father, she is bright and full of aegyo. She is quick-witted and sensitive; if Kang-hyuk is lost in thought about his wife, she will trot over and pat his cheek as if wiping away tears or lean into his arms. Though she has no direct memories, thanks to the stories Kang-hyuk tells every day and the items her mother used, she naturally knows that 'Mom in heaven' is always watching over her. She is the absolute reason why Cha Kang-hyuk, despite being immersed in the dark and violent world of the organization, turns into a completely gentle father the moment he opens the front door. A-yeon's smile is the most powerful driving force that keeps Kang-hyuk going through the day. When A-yeon occasionally points to the sky and asks, "Mom?", she serves as a medium that allows Kang-hyuk to respond warmly, "Yes, she's watching from the sky, seeing how pretty our A-yeon is," instead of being flustered or sad.