In Episode 4 of "Filing for Love," Ki-jun discovers that I-na is a nude model for the art studio, causing him to be shocked for a moment before regaining his composure and hastily leaving the premises.
The next day, Jae-yeol introduces James, a foreign innovator skilled in AI, with the hope that he will elevate Haemu to new heights. Meanwhile, Ki-jun decides to avoid I-na altogether, but fate has other plans. They end up being crammed into the same elevator after I-na insists on getting him coffee.
Later, Jae-yeol and Sung-yeol try to impress their father while playing a game, with Mu-tae being closer to Sung-yeol as they joke around. Back at the office, the workers create a competitive atmosphere reminiscent of "The Hunger Games" as they gossip about who to support.
Meanwhile, I-na learns from Min-su that the investigation into a worker at Haemu Electronics in Jeju has been assigned to the research center there. She decides to take over the case herself and asks for a volunteer to join her. As luck would have it, Ki-jun ends up being chosen.
On the ride to Jeju, I-na refuses to discuss the art studio incident. At Haemu Electronics, the junior engineer Lim Ha-kyong, who is being investigated, refuses to cooperate when James interrupts the questioning.
I-na and Ki-jun realize that there is more to the story. Despite Ki-jun's attempts to speak and reassure Ha-kyong, she insists on taking responsibility for everything.
Back in Seoul, the audit team indulges in their brief moment of freedom, relaxing and enjoying the little liberties they have. Sungyeol drops by and extends an invitation for a team dinner.
Upon learning that Sung-yeol is taking I-na’s team out for dinner, Jae-yeol insists on joining, causing panic among the team members. The reason? Jae-yeol and Sung-yeol have different tastes; one craves seafood, while the other can’t have it.
Ki-jun is puzzled by I-na’s sudden move to befriend James and spend the entire day with him. However, she clarifies that it’s all part of her work and asks him to go along with it.
Gwang-II keeps calling Ki-jun, asking for help in choosing a restaurant for the team dinner. They think it would be better if I-na picked the restaurant to spare them the difficult task. Unfortunately, Ki-jun has no time to ask I-na. In the end, Da-ye saves the day by finding a restaurant that serves both seafood and barbecue.
In the evening, I-na and Ki-jun bid a reluctant farewell to James and pretend to be heading back to Seoul. Instead, they follow James to a hotel, hoping to catch him red-handed as he sexually assaults Ha-kyong.
At the hotel, I-na orders Ki-jun to use the stairs to find James’s room. They then pretend to be a couple and insist on getting the closest room to James’s. As they wait, I-na admits that she feels embarrassed by the art studio incident. To make her feel more at ease, he offers her some cushions while she spies on James through the wall. Ki-jun complains of being thirsty and opens the wine bottle in the room. They drink as they wait for Ha-kyong to arrive.
Back in Seoul, the team dinner goes well, but Jae-yeol is disappointed that everyone seems to like Sung-yeol and that I-na is absent.
Hyun-kyu calls Ki-jun to inquire about their whereabouts, and I-na explains that they will be spending the night at the hotel. Ki-jun worries that her explanation might lead to a misunderstanding.
After dinner, A-jeong requests the driver to halt and fetch painkillers for Jae-yeol. She reaches out to comfort him, but he pulls away. This prompts her to ask if her feelings for him make him uncomfortable.
Through a flashback, we learn that a week after obtaining her job at Haemu, A-jeong was attacked by loan sharks who loaned money to her brother. They took everything they could and insisted that she pay the loan. She went to the office and found Jae-yeol still working in the early morning. Upon seeing her suitcase, he offered to let her stay in one of his apartments. She initially thought that he was doing it for sexual favors, but he proved her wrong. Since then, her feelings for him have only grown. She worries that he torments himself with work and tries to help him. One night, she kisses him, but he calls it a mistake and walks away. Even so, she refuses to give up on him.
At the hotel, Ki-jun and I-na bond as she explains why she models for the studio. She says it helps her breathe and relieves her stress from work. Ki-jun is flustered when she asks what was so shocking about seeing her naked. Fearing it might lead to a misunderstanding, Ki-jun volunteers to get naked before her, and she teases him back.
He gets up, and they stumble onto the bed with I-na pinning Ki-jun below her. It takes a few seconds and the sound of the elevator for them to regain their senses. They use the peephole to see Ha-kyon heading to James's room.
Inside the room, James forcefully demands to know what Ha-kyong told I-na and Kijun. She calmly responds that she never mentioned him, which prompts a threatening response from him. Hakyong, visibly scared, begins to cry as he approaches her. Just then, I-na and Ki-jun knock on the door, interrupting their confrontation.
James is surprised to see them and asks what they are doing. Without hesitation, I-na punches him and saves Ha-kyong. Ha-kyong is relieved and moved that someone finally took action against James. She tells them everything that had happened, and the next day, I-na and Ki-jun clear James's office.
They drive back to Seoul, and Ki-jun is once again subconsciously unaware of how he keeps trying to make I-na comfortable. After wrapping up James's case, Ki-jun asks I-na why she fired him. She coolly responds that what James did was a crime. Unfortunately, Jae-yol doesn't take the news well when I-na reports the case to him.
We don't see what happens next, but when Ki-jun and A-jeong rush into Jaeyeol's office after hearing something break, they find I-na in a disheveled state. Later, Ki-jun gives her a paperclip to help button up her shirt. That evening, A-jeong questions Ki-jun on what happened between him and I-na. Obviously, Ki-jun insists that nothing happened, but A-jeong doesn't believe him.
The next day, Ki-jun presents the final report on James, and I-na's hand lightly brushes against his. She returns the paper clip and thanks him for helping her. Ki-jun puts that paperclip on his desk as if it were special. Unfortunately, he gets another email from the anonymous sender. This time, there is a picture of I-na being embraced by a man whose face is obscured. The email puts Ki-jun in a foul mood, and when I-na mentions that he can come to the art studio, he turns her down and treats her coldly.
Stressed and annoyed, Ki-jun heads to the convenience store to vent to Rina. She is baffled at Ki-jun's reaction since he is getting closer to finding the truth about I-na. She points out that he should be happy. Ki-jun himself can't explain why he is annoyed.
On his way home, he changes his mind and goes to the art studio. He finds I-na modeling. He sits down and starts sketching. She patiently waits for him to finish drawing, even though everyone else has left.
She finally comes down to check his drawing and marvels at how pretty she looks in it. He confesses that he finds her pretty, and they suddenly start kissing fervently. The scene is filled with passion and intense emotion, as their kisses become more intense with each passing moment.
