The ninth episode of "To The Moon" opens with the relentless pace of Ji-song's work, her determination to complete her tasks swiftly so that she can pick up Wei Lin at the airport that afternoon. However, Oh Dong-gyu is not one to give up easily. He heads to a salon, indulging in a full makeover with a new suit, determined to impress her.
Ji-song receives a call from Wei Lin that shakes her to the core. He informs her that his mother has fallen ill, and their trip to South Korea has been cancelled. In addition, he reveals that he spent his money on a pair of shoes instead of using it to come see her. Heartbroken, Ji-song tells Wei Lin that they should break up. As she is about to walk into oncoming traffic, Dong-gyu saves her, only for her to see his face and scream in horror, running away.
Meanwhile, Da-hae and Ji-woo are going strong but Da-hae panics at the thought of people seeing them together. One day, Da-hee sees them drive off together. At work, everyone is in awe of Dong-gyu's new look. In the marketing team's meeting, Da-hae proposes a personalized snack box as a new idea, which is well-received. We then see that Da-hae has prepared a card and a box of cookies to give to Ji-woo. She takes them up to his office and leaves them on his desk, unaware that Ji-woo and Manager Ko are about to enter the room. To make matters worse, Da-hee arrives as well, and out of hunger, she takes one of the cookies that Da-hae left for Ji-woo. However, she faints after taking a bite.
She ends up in the hospital, but Manager Ko believes the incident is an attack on Ji-woo himself and is determined to get CCTV footage. Da-hae manages to delay this by buying everyone a round of coffee and cookies. In the hospital, Da-hee wakes up and while chatting with Ji-woo, she mentions that Da-hae said she's not seeing anyone. On the drive home, Ji-woo calls Da-hae and asks her if she'll ever make their relationship public. But she's at work and quickly cuts the call when a colleague comes by with more tasks for her. Ji-woo is venting to his friend when he realizes he left Da-hae's letter in the office.
As Eun-sang navigates the challenging waters of her workplace, she confronts a team rife with incompetence and delays, leading her to adopt a military-like demeanor to inspire them to excel. In the accounting department, Ji-song shies away from Dong-gyu, prompting Soo-jin to speculate that Ji-song has developed a crush on him.
When Da-hee returns to work with a vengeance, determined to catch the cookie thief through CCTV footage, she inadvertently puts Da-hae in a bind. Da-hae shares her predicament with her friends and hustles to the security room alongside Da-hee. Eun-sang and Ji-song cleverly distract the security team members, allowing Da-hae to swiftly navigate through the footage. However, Da-hee catches her in the act, yet pretends otherwise.
Later, Da-hee reveals to Da-hae that she has the letter left for Ji-woo by the 'perpetrator' and plans to deliver it to the police later. She informs Da-hae that it's in the break room, and Da-hae sneaks it out of Da-hee's locker later.
Meanwhile, Ji-song finds herself in hot water when she botches a document. She rushes into a meeting to retrieve the paper from a senior manager's hands and then makes a hasty retreat. Unfortunately, she trips and falls, and Dong-gyu comes to her rescue just in time. Suddenly, the building's lights go out. As Da-hae is leaving the office building with the letter, she gets stuck in the revolving doors. Coincidentally, Ji-woo also gets stuck there. She informs him that she found the letter, but the envelope proves to be empty.
Ji-woo then stuns everyone by revealing that he has the letter. He plumbed the depths of the trash can in search of it, for it holds a precious sentiment to him. He unabashedly confesses his growing affection for her, a confession that seems to touch Da-hae deeply. She manages to push the door open, and when they're all out, Da-hae declares her undying affection for Ji-woo, no longer hiding it.
Ji-song confesses to Oh Dong-gyu that she's upset because despite his good looks, she doesn't feel any butterflies in her stomach. She finds herself more drawn to money than to handsome men. Dong-gyu chuckles it off and assures her not to worry about him.
Meanwhile, Eun-sang and her team lose the client. Her colleagues offer heartfelt apologies, which move Eun-sang deeply. They go out for drinks, where Eun-sang apologizes for making things more difficult than they already were.
The next day, Manager Ko informs Da-hae that he has submitted her proposal for a personalized snack subscription. He also reveals that he saw the CCTV footage and knows she's dating Ji-woo. He then commends her on how she's changed and become more confident. However, the drama isn't over yet. A message from Hoppang Bite announces that Ji-woo has resigned.
An epilogue in To The Moon Episode 9 shows a flashback where Ji-woo asks Da-hee why she ate the cookie on his desk despite knowing she has a peanut allergy. She also pretends she threw the letter out when it came into her possession "by accident." But Ji-woo isn't fooled and questions her true intentions.
