Episode 3 of "Our Universe" unfolds with the signing of a roommate agreement between Hyun-jin and Tae-hyung, stipulating that Tae-hyung will reside at Hyun-jin's abode for precisely one month. At work, Tae-hyung requests a month's leave to attend to Woo-joo while Hyun-jin is at work. His boss agrees to grant the leave, but only if Tae-hyung steps in as the photographer for a shoot at a motel. Without hesitation, Tae-hyung accepts and heads to the motel. There, he is spotted by Jo Moo-saeng, the manager of the renowned photographer Amy Choo. Manager Jo offers Tae-hyung one million won to assist Amy Choo for a one-day shoot, but Tae-hyung declines, adhering to his vow to abstain from photography.
The next day, Hyun-jin embarks on her first day at work, attending various training sessions. Returning home, she and Tae-hyung discover that the hot water has been cut off due to a faulty boiler that requires a million won for repairs, which Hyun-jin cannot afford. That night, they resort to heating water on the stove to bathe Woo-joo.
On Hyun-jin's first official day with the team, she is dismayed to learn that one of her colleagues recognized her from a video that Tae-hyung had shared of bringing Woo-joo to the office. The video has garnered over a thousand views, further embarrassing her. Her shock deepens when she realizes that her manager is Park Yoon-seong, her first love. He introduces himself without mentioning his recognition of her.
At home, Tae-hyung seeks tools from the neighbor to fix the boiler and is offered assistance by the neighbor himself. When questioned about his relationship with Hyun-jin, he is mistaken for Hyun-jin's boyfriend. Ultimately, the neighbor fails to repair the boiler and leaves it in a worse condition than before.
In this beautifully crafted scenario, every detail is meticulously rendered to ensure that the essence of the story remains intact while enhancing its emotional depth and visual appeal.
Hyun-jin returns home and attempts to communicate with the landlord about the boiler. She and Tae-hyung engage in a heated debate over the text message they should send, ultimately sending him a rude image by mistake. Over the next two days, Hyun-jin has to endure cold showers. On the third day, Tae-hyung notices that she's getting sick and decides to take on the photography job for Amy Choo. He enlists the help of his friends to babysit Woo-joo and contacts Jo Moo-saeng. He secures the job and assists Amy Choo in a model's shoot. Despite Manager Jo's warning not to give Amy his own opinion, Tae-hyung offers his take on the lighting - he says he can take the risk since he's just a one-day employee. After the shoot, Tae-hyung's friends point out that Amy Choo used to be his idol, but Tae-hyung insists this was just a one-time thing.
At the office, Yoon-seong realizes that Hyun-jin is sick and offers her a ride home. They finally address the fact that they used to know each other and part on good terms. A flashback shows Yoon-seong about to confess his feelings to her when she gets a phone call. She returns and tells him she's leaving for a language program and likely won't see him again.
When Hyun-jin comes home, she's annoyed to find the place in a mess but is pleasantly surprised when Tae-hyung tells her the boiler's fixed. After a nice, hot shower, she and Tae-hyung have a drink. She offers to pay him back for the boiler in installments but he tells her to let it go. They decide to get through the rest of the month in peace. However, it seems unlikely as the next morning, after finishing many bottles of wine, the two wake up in the same bed.
