Continuing from Episode 11, we see Gyeore still shocked after the man from Room 403 suddenly woke up. In this scene, he was seeing things but it turns out that the kid he was seeing was a grandson of one of the patients.
When Gyeore went back to Room 403, the patient is back asleep.
The next morning, Gyeore immediately went looking for Yeonjoo.
He tried to tell her what happened last night but Yeonjoo was too busy to listen to his story.
Later that night, we see Yeonjoo dead-tired after her shift. She looked like she was sleep-walking but when Gyeore talked to her, she bluffed by saying that she is Seo Yeonjoo who is as strong as steel.
Gyeore then offered to take her home and inside the car, we see Yeonjoo falling asleep like a baby.
She woke up when Gyeore asked her "What if the man from Room 403 wakes up", Yeonjoo said that he should inform her right away because he is a dangerous man, and then went back to sleep again.
They arrived outside Yeonjoo's house and here, Gyeore just found out that Mr. Kang has already left to receive his chemotherapy.
Gyeore was mad about not knowing it but Yeonjoo tried to comfort him by asking, "Would you like some ramyeon?".
It wasn't the "Would you like to eat ramen?" thing from other K-dramas, though, as we see the two eating at a food stall. Also, it turns out that Yeonjoo was the one who needs comforting as she's the one who misses Mr. Kang the most.
The next day, Yeonjoo and Dr. Yang went to check on the patient from Room 403. At this point, they are suspicious about whether he is not waking up on purpose or not.
Meanwhile, Gyeore's new recruits, the two grand kids of one of their patients managed to put a smile on Yeonjoo's face after seeing them do some voluntary works.
As the day ended, we see Gyeore taking Yeonjoo home once again. He asked another "what if" question but he still couldn't tell her that the man from Room 403 is already awake.
That's also after Gyeore found out that the man from Room 403 could be his Father.