Episode 4 of Our Universe unfolds with Hyun-jin and Tae-hyung waking up in the same bed, their consciousness slowly returning to them amidst memories of a drunken night before. A flurry of flashbacks reveals them downing bottles of wine, ultimately leading them to Tae-hyung's room where he proudly displays his photography award, only for Hyun-jin to break into tears over her late sister. This traumatic incident prompts them to vow to abstain from alcohol in the future.
Hyun-jin confides in Se-yeon about her feelings, though the latter wonders if she now views Tae-hyung as a man. Hyun-jin dismisses this notion, but the air around them is charged with an unspoken understanding. Meanwhile, Tae-hyung's friends inquire about Hyun-jin's attractiveness, further complicating their already awkward co-existence when they return home. Both begin to view each other through new eyes, with Tae-hyung inquiring about the unresponsive landlord due to multiple repair needs in their shared space.
The next day at work, Hyun-jin's colleagues continue to speculate about her identity as the viral lobby girl from a certain video. As they work on acquiring a new client, GloMarket—a company that previously rejected Park Yoon-seong's proposal—Yoon-seong is elated to see Hyun-jin's research and asks her to draft the first proposal. She accepts.
While taking out the trash, Tae-hyung encounters his neighbor, Bae Du-sik, and his mother, Park Ae-ja. When they return home, Hyun-jin requests Tae-hyung to look after Woo-joo for additional hours daily until she completes her proposal work. He reluctantly agrees. Over the next few days, Hyun-jin works tirelessly.
One day while cleaning, Tae-hyung notices the glow-in-the-dark stars adorning Hyun-jin's room—a space she can no longer sleep in due to traumatic memories. Flashbacks transport us back to their drunken night together when Hyun-jin showed Tae-hyung these stars. She recounts how they lived in a basement apartment that flooded during rains, leading Hyun-joo to create a game by placing a glow-in-the-dark star for every cleaned spot. Hyun-jin also remembers her sister's kimchi pancakes and regrets her final rude words spoken in that same room, preventing her from sleeping there again.
Currently, the heavens opened up, and Tae-hyung dived into making kimchi pancakes for her. As Hyun-jin was about to return home, Yoon-seong asked her to extend her work hours. Later, he offered to drop her off and discuss their strategy on the way. However, she persisted in concealing her residence and avoided mentioning her sister as well.
Tae-hyung dropped Woo-joo off at his neighbor's house and waited for Hyun-jin at her bus stop, carrying an extra umbrella. That's when he witnessed Yoon-seong dropping Hyun-jin off and handing her his own umbrella. Hyun-jin was taken aback to see Tae-hyung waiting with an umbrella. She was even more touched when she saw the pancakes at home.
Soon, Amy Choo's photoshoot went live. She even mentioned Tae-hyung's name in the magazine. Hyun-jin bought a copy of the magazine and congratulated him. Tae-hyung received a call from Amy Choo herself, who sternly told him to come for a job the next day and bring his camera. He wasn't inclined to go, but Hyun-jin encouraged him.
Another flashback revealed that Tae-hyung showed Hyun-jin the camera his brother had given him as a child and explained its significance to him (without revealing it was his brother's). He said he still yearned for photography.
At present, Hyun-jin urged him to go on the job and find out what it still meant to him. He agreed and asked if she could make it home that day. She said she would but that evening, Yoon-seong asked her to work late again. She apologized profusely to Tae-hyung, who decided to take Woo-joo with him. He met Amy Choo, who gave him a test, instructing him to take pictures and have the prints ready in three hours.
Meanwhile, Hyun-jin and Yoon-seong were huddled in a hotel room, pouring over their proposal so that Yoon-seong could meet some clients at the nearby airport. She reminisced about how even in college, Yoon-seong had been her manager and they'd stay up all night working. He smiled and replied that he stayed up to spend time with her.
As Tae-hyung worked on his photographs, Woo-joo ended up falling down and getting hurt. Tae-hyung rushed him to the hospital, where the doctors asked for Woo-joo's guardian. Tae-hyung called Hyun-jin, but she couldn't pick up because she was at the airport with Yoon-seong. She only saw his call on her way back and then rushed to the hospital.
Woo-joo had been treated and was asleep now. But Tae-hyung berated her for being late and said she couldn't even take responsibility for herself, much less for a baby. The doctor later told them that Woo-joo's cut would heal, but the more pressing matter was his mental state. He said that babies sense everything and that Woo-joo seemed to be reacting to emotional stress.
The next day, Tae-hyung regretted being so harsh to Hyun-jin. He picked up some food for all of them. They were about to eat when the doorbell rang. It was Yoon-seong! He was the landlord!
(Note: I have tried to maintain the meaning of the original text while adding more descriptive language to make the scene more vivid and engaging.)
