The fifth episode of "Had I Not Seen the Sun" commences with Yun-chen pouring her heart out to Hsiao-tung in a letter, penned in the year 2008. In a poignant flashback, we witness young Yun-chen being reared under the stern watch of her grandmother, who harbors a deep-seated resentment towards her mother, blaming her for the demise of Yun-chen's father. As Yun-chen delves into her parents' tragic past, she discovers that their suicide left her mother with superficial burns while claiming her father's life. Amidst her tumultuous childhood, she found solace in watching young Hsiao-tung dance, a sight that ignited a friendship that has since blossomed into a deep bond. She describes Hsiao-tung as the sun that shone warmth into her life, ending the letter with a yearning inquiry about Hsiao-tung's whereabouts and what she might be doing.
The present scene finds Hsiao-tung assisting Yun-chen in eluding her grandmother's watchful eye, escorting her home and informing her parents of her overnight stay. As night descends, Hsiao-tung is consumed by guilt, blaming herself for Yun-chen's circumstances, and finds solitude in her insomnia. Impulsively, she decides to take a stroll to the convenience store for a drink, where she collides with Jen-yao. Jen-yao, fleeing from debt collectors outside his home, purchases a bowl of noodles at the store. When Hsiao-tung arrives, Jen-yao perceives her somber demeanor and surmises that it stems from Yun-chen's predicament.
Hsiao-tung confides her intention to reveal the truth to the school the next day, but Jen-yao cautions that such a move would undermine Yun-chen's noble intentions. He implores Hsiao-tung to join him for a ride, an offer she accepts. Outside the convenience store, Ouyang-ti awaits a delivery when he catches sight of Jen-yao and Hsiao-tung together, his fury palpable, especially as he witnesses Jen-yao assisting Hsiao-tung with her helmet before they drive off together.
During their ride, Hsiao-tung inquires about Jen-yao's closed eyes and outstretched arms during his fall, revealing it as a means to leave all his problems behind. He invites Hsiao-tung to try it, and she does so, holding Jen-yao and leaning on his shoulder. In that moment, she admits that being with him feels like they're whisking them away to a place where no one knows them.
The dawn found Yun-chen borrowing Hsiao-tung's school uniform, determined to face the day head-on. As she arrived at school, Ouyang-ti's gang taunted her and Jen-yao, both without gym attire. Their jokes turned into whispers that Yun-chen and Jen-yao had spent the night in a motel. Enraged, Yun-chen lashed out, slapping one of them. The boy swung back, but Jen-yao intervened, striking him until blood stained his knuckles. Ouyang-ti saw his chance, ordering his boys to take on Jen-yao.
Just as they were about to gang up on him, a teacher appeared on the scene, leading them to the military office. Ouyang-ti and his friends concocted a tale, pinning the blame solely on Jen-yao. According to school rules, those who initiate a fight receive a major demerit, those who retaliate receive a minor demerit, and those who witness the incident without reporting it to a teacher receive a warning.
Jen-yao was one major demerit away from expulsion, and the teacher urged him to write a withdrawal letter. He was unfazed, insisting on being expelled. But Yun-chen intervened, reminding the teacher of their promise the previous day when her grandmother picked her up from school. They had agreed that the issue would remain unspoken as long as Jen-yao and Yun-chen honored their pact. Therefore, Ouyang's group had initiated the conflict by taunting Yun-chen, and she had retaliated by slapping one of them. Jen-yao had defended her, leading to their being ganged up on. The teacher had no choice but to let the matter rest, ordering Ouyang's group to write apology letters instead.
Jen-yao, following Yun-chen, expresses his gratitude for her assistance. Yun-chen, however, rebukes him sharply, reminding him that they are not friends and that he should not act too familiarly towards her. She issues a stern warning, that he should lead his own messed-up life alone and not drag Hsiao-tung into it. She warns him that if anything happens to Hsiao-tung, she will come for him.
That evening, Yun-chen and Hsiao-tung walk home together. Yun-chen feels uneasy about her grandmother's silence all day after her night out. She also notices that her grandmother did not pick her up from school and did not send a driver.
When they arrive at Hsiao-tung's home, they find police officers talking to his parents, claiming that they were reported for kidnapping. Yun-chen hurries back home to her grandmother, who threatens to ruin Hsiao-tung's family business if Yun-chen continues to associate with him.
Meanwhile, Ouyang-ti's group remains enraged about Jen-yao and wants to beat him up. But Ouyang-ti thinks that simply buttering him up is not enough. Instead, they should do something that completely ruins his life, so that whenever he thinks of them, he realizes that he messed with the wrong crew. Ouyang-ti calls someone and asks for a favor.
The next day, Yun-chen's grandmother confiscates her phone and tells her that she will not be going to school. She had already sent someone to handle the withdrawal procedures. Jen-yao overhears this from Ouyang-ti's group and informs Hsiao-tung during lunch break. Hsiao-tung tries calling Yun-chen, but her calls go unanswered.
After school, Hsiao-tung goes to Yun-chen's house but still cannot reach her. Inside the house, Yun-chen is crushing pills into powder. Meanwhile, at the convenience store, Jen-yao is jumped by creditors who carry him back to his house and force him to sell drugs to pay back his father's loans. Jen-yao refuses, so the gang members hold him down while the leader forcibly injects him with the drugs. As Jen-Yao drifts in and out of consciousness, he vaguely sees and hears Ouyang-Ti taking a picture of him.
