The episode begins with a flashback of Deok-mi and Yoon-jae playing as kids, this time with Eun-gi in their little group. Back in the present, Ryan wakes Deok-mi with a kiss and wishes her happy birthday. She wants to sleep in and Ryan suggests handing in their resignations and staying in bed all day. They eventually start getting ready for work together. Ryan hilariously tries to cook seaweed soup for Deok-mi. They stop by her place so she can change and jam to White Ocean’s song on their way to work.
After a meeting for the exhibition, Ryan asks Deok-mi to make time for him in the evening. Deok-mi’s mom stares at a photo of Yoon-jae and Deok-mi as kids and thinks back to waiting for Yoon-jae’s mom in the playground. She wonders why Eun-gi brought up Yoon-jae out of the blue.
Deok-mi walks into the restaurant Ryan has reserved for her only to find Si-an waiting to wish her with a cake. Turns out Si-an is Ryan’s surprise for her. She thanks him for making her the happiest fangirl in the world and he gives her exactly 20 minutes alone with Si-an. He spends that time with his mom, who tells him that his real birth date is September 12 and hands him some pictures from his childhood.
Later that night, while dropping Deok-mi home, Ryan shows her his childhood pictures and demands to see hers. He has another surprise for her that hasn’t shipped yet, and he asks her to wait for it.
Eun-gi remembers that the boy from the playground was also called Yoon-jae and drops by to ask Deok-mi about it. He happens to see Ryan’s childhood photos and leaves without asking her about Yoon-jae. Deok-mi sends Ryan pictures of her childhood. Looking at a photo of Deok-mi’s mom, Ryan realizes that the woman he remembers abandoning him at the orphanage is her.
Eun-gi comforts Deok-mi’s mom by telling her that she had no choice but to abandon the kid, before divulging that Ryan is Heo Yoon-jae. Ryan takes Deok-mi out to ask if she remembers everything from her childhood when Deok-mi gets a text from her mom, asking her to come home after work. Ryan visits Eun-gi to talk about seeing him and Deok-mi’s mom in his memories. “It’s been a long time, Heo Yoon-jae,” Eun-gi says.
Deok-mi is shocked at learning the truth about Yoon-jae and walks out on her parents. At home, she stares for a long time at the younger Yoon-jae’s pictures and slowly starts to remember the times she spent playing with him in her childhood. Eun-gi sits outside her building and remembers Ryan asking about the fourth kid in his memories. That was Deok-soo, Eun-gi had told him, revealing that Deok-mi didn’t remember him.
Deok-mi’s dad visits her apartment to talk to her. She used to have a little brother named Deok-soo who had passed away after getting into an accident. Deok-mi had been with him at the time but had lost her memory due to shock.
After her father leaves, Deok-mi stares at the photo of her little brother for a long time, until she suddenly remembers the accident and bursts into tears. She runs over to her parents’ house to apologize to her mom for forgetting everything. “I was able to keep living thanks to you,” her mom tells her. She meets Eun-gi and thanks him for being a comfort to her parents all these years. Keeping Eun-gi’s advice to give Deok-mi space in mind, Ryan refrains from calling her.
The next day at work, Deok-mi confesses to Ryan that she wanted to hide but then decided not to be alone. Her mom visits the gallery to apologize to Ryan in person, but Ryan just thanks her for taking him in and loving him. Deok-mi informs Ryan of her plans to visit her brother’s resting place and he decides to accompany her. They agree to make lots of memories together to replace the painful ones.
Director Eom is still jealous that Hyo-jin called someone else her mom and sets out to bring her home. She tries to force Hyo-jin to get into her car but Deok-mi’s mom gets there. The bickering mother and daughter end up at Deok-mi’s house, where Deok-mi’s mom makes the two reconcile and sends Hyo-jin home.
Si-an and Da-in discuss working together again. The staff at Cheum works hard for the exhibition. After work, Ryan brings Deok-mi over to his place because her birthday gift has arrived. He places a hand over her eyes and leads her to his painting room, unveiling a painting of her. She tears up when he reveals that he can paint again and tells him that the painting is perfect. They smile as they remember the first time they met as kids.