In the eleventh episode of "In Your Radiant Season," the story unfolds with Ha-ran discovering Chan's notebook, revealing his notes on Hyeok-chan and Su-jin. She returns home, piecing together the puzzle, realizing that it was Chan all along who had been messaging her. Chan, who had spent the entire day searching for her, finally locates her at a café. Confronted by Ha-ran, he confesses that he can't differentiate between him and Hyeok-chan. She accuses him of being insincere and throws the pen at him. Without giving him a chance to explain, she storms off, believing that he's proven that she's not allowed to be happy.
At home, she gathers all the things he'd given her and throws them into trash bags, including the original engraved pen. Despite falling ill, she insists on going to work. On her way out, Chan arrives and tries to give her the tablet with his story, but she refuses. He tries again at work, but she shuts him out completely. Meanwhile, the other employees comment on Tae-suk's absence from the office.
A flashback reveals Tae-suk trying to quit his job after Ha-ran's parents' death. Na-na tells him to focus on college instead. In the present, Tae-suk tries to quit once again due to feeling like a failure to Na-na. She reassures him that he couldn't have prevented either incident and encourages him to put the burden down. Outside the hospital room, Ha-young overhears the conversation and later tells Tae-suk it's not his fault. She offers him the sweet she first gave him when they met.
Mr. Park calls Chan to check in on him, but he insists that he's doing fine. He tries again to give Ha-ran the tablet, but she believes it won't change his lies and refuses to take it. As she leaves, Chan feels a burst of pain and drops the tablet, which is then shattered by a passing car.
Elsewhere, Ha-dam and You-gyum practice You-gyum's pitching skills, but it doesn't go well. You-gyum tells her to go home since his friends are coming over, but she returns with snacks for them. There, she finds him in tears because he doesn't believe his leg is getting better. Ha-dam hugs him and lets him cry it out.
That night, Nana confides in Mr. Park about her fear of having to shave a part of her hair. In response, Mr. Park surprises her with a hat he knitted himself while she was sleeping. She is delighted and Mr. Park then proposes to her, asking if she'll stay by his side and rest after the surgery.
Mr. Park goes home to find Chan in a state of distress. He's worried that Ha-ran will return to her old self, and realizes that Chan has a fever, after which he soon passes out. Mr. Park helps him to bed, and a flashback reveals that Chan had previously told Mr. Park the whole truth. Mr. Park believes that his sincerity can make a difference and encourages him not to wait for the perfect moment but to simply tell her.
Meanwhile, Ha-young finds Ha-ran upset and tries to comfort her, helping to bring down her fever. But in the middle of the night, Ha-young wakes up and realizes that Ha-ran has left the house and forgotten her phone behind. She calls Chan and he rushes out to look for Ha-ran.
Chan realizes that she must be at the campsite they visited, where they discussed how the stars and moon could never be together. While driving there, Chan feels some pain again and it triggers more memories. He is forced to stop the car and now remembers punching Hyeok-chan and causing the waste container to fall. Could he be the reason for the fire? When he finally finds Ha-ran crying at the campsite, he's unable to approach her.
We then see him approach Su-jin and ask if he hit Hyeok-chan. She confirms that he did. A flashback shows Hyeok-chan returning from his trip. Chan tries to talk to him but he tells Chan to speak to him later in the lab. Chan does so and tells him the truth, leading to heated exchanges and Chan hitting him. At present, Chan asks Su-jin if the fire started because of the waste container and she confirms it did. It was all his fault.
Ha-ran returns home to a worried Ha-young who tells her that Chan was out driving, looking for her, and wasn't picking up his phone now. Despite her instincts, Ha-ran becomes worried and goes to look for Chan.
At the hospital, Su-jin learns about Chan's condition, unaware of the burns and shrapnel in his head. We now learn that his condition can also lead to hallucinations and memory distortion. Are any of the Boston flashbacks real?
Elsewhere, Ha-ran realizes that Chan has left, seemingly for good. She finds a Post-it on her car that says "end of trial." Life goes on and eventually, Ha-ran takes Chan's tablet and sees the first page of his story.
