In episodes 9-10 of The Only One, Tian surprises everyone by joining in the sporting activities, something he’s never done before. However, it’s clear that his main motivation is Sheng’s participation. Since the sporting events are point-based, their class hopes to outperform others with both Sheng and Tian competing.
At the same time, Xiao Xi is troubled by Qi Jiahao, a former student he tutored. Xiao Xi had seen Qi Jiahao leave his classmates in frustration. When confronted, Qi Jiahao reveals his anger, feeling overshadowed by Sheng, who gained class approval effortlessly, while he worked hard for acceptance. Miss Jing notices Xiao Xi’s downcast mood and tries to lift his spirits, leading to a lighthearted moment where Xiao Xi affectionately pulls her closer, teasing her for being cheesy.
During Sports Day in The Only One, Tian and Sheng help their class secure the top spot in the relay race. Principal Xu promises the class a steak treat if they win the championship. However, things get tense when Tian’s father shows up, attempting to speak with Tian, who chooses to ignore him.
As the teacher’s race approaches, Xiao Xi and Mr. Lim realize that Miss Jing is missing. They search for her and discover she has been confronted by the same thugs from earlier. Xiao Xi and Mr. Lim rescue her, but Xiao Xi leaves Mr. Lim to tend to Miss Jing’s wounds, thinking he might have feelings for her.
Meanwhile, Tian and Sheng claim victory in the high jump and long jump, although Sheng slightly injures his ankle during the event. Tian notices Sheng’s injury and decides to drop out of the tied-leg race, carrying Sheng to the school clinic. After Sheng is treated, Tian playfully draws ellipses on Sheng’s bandaged leg.
The other students arrive to cheer up Sheng by writing on his bandaged leg. Unfortunately, due to Sheng and Tian’s absence, their class loses the final race, costing them the championship. However, the boys, except for Sheng due to his injury, had made a bet to run naked around the field if they lost. They follow through, despite the principal’s protests, amusing everyone and even impressing him.
In the next episode, Sheng is forced to rest at home to heal his leg. Miss Jiang is particularly attentive, but Sheng reassures her not to worry, embracing her and finally accepting her into his life.
Sheng grows bored during his recovery and misses Tian, even going to his quiet room. Tian constantly receives texts from Sheng about his boredom, so he decides to prepare exam questions for him.
Meanwhile, Xiao Xi discovers surveillance footage of the thugs harassing Miss Jing. Mr. Lim worries they may be taking things too far, but Xiao Xi reminds him of how he saved Mr. Lim’s life when he was attacked by hoodlums while protecting a historic wall. Since then, they have been inseparable friends. Mr. Lim is about to reveal why he followed Xiao Xi from abroad to Thailand, but a call from Miss Jing interrupts them, leaving tension between the two as they hide their true feelings.
Miss Jing later asks Xiao Xi to help her pick a gift for someone she likes. She admits to having pursued Xiao Xi in the past, but he never noticed her. However, Xiao Xi soon realizes the gift is for Mr. Lim when she chooses a cup he likes, leaving Xiao Xi upset.
Meanwhile, when Sheng returns to the dorm, Tian teases him about gaining weight, causing Sheng to get mad and nearly stumble while trying to hit him with crutches. Tian catches him, and they share a flustered moment. Sheng also notices a couple kissing in the dorm, confirming rumors that students use the dorms to date.
Later, Sheng recognizes Shi Yu as one of the students caught kissing, but Shi Yu tries to deny it. Tian quickly guesses he was with his girlfriend.
Sheng is confused by Tian’s caring behavior, especially when Tian helps change his bandages and insists he take the lower bunk. The next morning, Tian brings Sheng breakfast and even offers to stay over to take care of him, but Sheng declines.
Xiao Xi notices the cup Miss Jing bought on Mr. Lim’s desk and asks if she has feelings for him. Initially, she denies it, but eventually admits the truth and asks for Xiao Xi’s help in understanding Mr. Lim’s feelings for her.
As the holiday break approaches, Tianyang and Shi Yu head home, and Sheng realizes he should have waited until the holiday instead of rushing to the dorm to see Tian. That night, a thief breaks into the dorm, causing panic. The supervisor suggests the students bunk together if they are scared, and Sheng suggests sleeping with Tian. Tian, regretting not sleeping with Sheng the previous time, agrees. As they sleep together for the first time, Tian realizes that Sheng has broken through his emotional barriers, and he wonders if their bond will lead to tragedy.
