Episode 5 of "In Your Radiant Season" picks up with Ha-ran inquiring about Chan's cryptic statement to his grandmother about not liking her. Chan explains that he didn't want to make her uncomfortable. As they journey to the villa in Gyeongju, they stop at a picturesque bridge, taking in the breathtaking view. Ha-ran confides that she lost her parents on the day of the first snowfall, and those days hold a special bittersweetness for her. She then brings up his mother, but he quickly changes the subject.
At the villa, Chan introduces Ha-ran to the rest of the animation team. In the morning, Ha-ran's team arrives, and they all get down to work. They go sightseeing in the village of Yangdong. While Ha-ran ponders over Chan's past, a flashback reveals how Chan left South Korea for Florence, where he decided to pursue his passion for drawing.
During lunch, Chan steals the eggplant from Ha-ran's plate, calling it "neon aliens." After some time, Ha-ran points out that she never told him she thought of them as neon aliens, but dismisses it as a memory lapse. Close call for Chan!
At the beach, Ha-ran sees a plane's vapor trail in the sky and talks about the day she went to the US. This triggers some of Chan's memories, but he can't quite piece them together.
Back in Seoul, Na-na has to quickly change her outfit because she fell and injured herself. She hides this from Ha-young and the others. Meanwhile, Ha-dam sees You-gyum leaving a jewelry shop and assumes he's bought couple rings for them. The truth is, he's bought a necklace with an SOS phone number for Na-na to wear in case of emergencies.
At school, Ha-dam's friend suggests that You-gyum bought something for So-ra. After work, Na-na meets Mr. Park, who shows her an LP of "La Vie en Rose" that he bought for her years ago in Chuncheon. However, by then, Na-na was already on a flight to Paris (using the tuition money meant for medical school).
In Gyeongju, Chan and the team are about to head back. Ha-ran forgets her scarf and goes back into the woods to look for it. Chan follows and they soon get caught up in a sudden rainfall, taking shelter until it stops. Ha-ran admits she's curious about Chan's past but he tells her he wants to keep that part of him a secret.
That night, the team convened on the beach for a mesmerizing barbecue, where Ha-ran even indulged in a few libations. Chan began to ponder whether he should reveal the truth to Ha-ran. She continued to pour her heart out to him about her relationship and thanked him for his unwavering friendship. To test her, Chan played a quick game with her, stipulating that if she won, he would confess the truth. She triumphantly won—but fainted before he could utter a word, revealing her lightweight status.
That evening, a piece of Chan's memories resurfaced. A flashback revealed Hyeok-chan's injured hand and the jingling sound of a woman's bracelet. Hyeok-chan had been cheating on Ha-ran with a woman named Su-jin. As Chan awoke in the present, he was filled with anguish, realizing the extent of Ha-ran's impending heartbreak.
In the morning, he took Ha-ran for a walk along the shore. She recalled the game but told him that he didn't have to divulge his past if he didn't wish to. He did speak about the person who had helped him heal, saying she had broadened his world. He vowed not to reopen old wounds to protect that person's happiness.
Back at home, Ha-young realized that Yeon Tae-suk had taken out the green onions for her when they were eating ttteokbeokki. But she dismissed it when she learned that Yeon Tae-suk also provided his grandmother with vitamins and his sister with tonics.
Soon, Ha-ran and her team prepared to return to Seoul. Chan showed her an iridescent cloud, saying it helped him get excited for the future—unlike vapor trails, which only symbolize things that have already passed. As homework, he gave her a film camera and instructed her to capture a photo of something beautiful every day until he returned to Seoul.
When they returned to the office, everyone was taken aback by Ha-ran's unexpected gesture of bringing coffee for everyone and engaging in cheerful conversations with them. In the elevator, Ha-young crosses paths with Tae-suk, who offers her a sweet and sour candy. A flashback reveals Tae-suk as a young student, meeting Ha-young at the atelier just before his interview with Na-na. She gives him a sweet and sour candy to boost his confidence.
At present, Ha-dam speaks with You-gyum and dismisses her suspicions about So-ra. However, we see So-ra calling You-gyum's phone after she leaves. Meanwhile, Ha-ran continues to experience a creative block with her work. Chan sends her a picture of an iridescent cloud that sparks an idea. She designs an outfit for Won featuring mother-of-pearl colors, similar to the cloud. Na-na is quite pleased with the result. Elsewhere, Na-na receives another visit from You-gyum. In addition to the necklace, he gives her a health drink and inquires about the bruise on her leg.
Chan, still in Gyeongju, calls Ha-ran and tells her he's making a reservation at a pizza place for their next full moon date. Over the next few days, they exchange texts, and Ha-ran takes pictures of things that make her smile. She confesses to Mr. Park that she's found the part of herself that used to find joy in the smaller things.
On the day of their pizza date, Chan decides to drive back to Seoul himself but not the way he came, as a truck swerves by his car. In Seoul, Na-na calls Ha-ran and says she wants her to take over the business. She plans on retiring soon and going to France.
After the meeting, Ha-ran sees missed calls from Chan and panics. She goes to the coffee shop where Mr. Park tells her that Chan had to suddenly return to the US. Ha-ran is incredibly disappointed, even more so when she gets her film developed and sees that Chan had taken photos of her laughing during the trip. The final shot shows a picture of himself smiling at the camera.
