Mo Guan Shan is an attractive boy with natural fluffy red hair and red eyes. He has a white peach skin tone. He's always seen wearing white and yellow based clothes. He has both of his ears pierced and outside school he often uses earrings. Although most of his classmates see him as a school bully because of his outside appearance and bad temper, in reality he is more of an outcast than anything else. His problematic behavior at school is most likely caused by the fact that he thinks people are thinking lowly of him. He's actually a very sweet boy underneath and seems to share a very lovely and stable relationship with his mother. For unknown reasons his father is in prison but he seems to believe in his innocence. He shows a tsundere side with He Tian. He is either mad at him for no special reason or gets easily flustered when the He Tian touches him or initiates any type of physical contact.
Mo Guan Shan starts as a "bully" who picks on Jian Yi and later physically hurts Zhan Zheng Xi. Shortly after He Tian, despite being friends with Jian Yi and Zhan Zheng Xi, begins to develop feelings for him and following him around, much to Guan Shan's disdain.
When his first kiss is stolen by He Tian he gets very angry assuming he was only making fun of him, to the point of crying and yelling leaving a speechless He Tian behind. After this event He Tian refrains from being too pushy but still pursues him anyways and despite everything Guan Shan seems to have start seeing him in a different light by always acting very aware and flustered at any kind of physical contact with He Tian.
When Mo Guan Shan is framed by She Li for assaulting a girl he is surprised to see Jian Yi and Zhan Zheng Xi helping him by clearing his name thus making become more friendly with the both of them. When he finds He Tian injured after fighting with She Li for his sake he is greatly touched and they share a moment where they interlace their fingers together and uses his own shirt to wipe He Tian's blood.
When Guan Shan accepts to go dinner with He Tian after finishing the job He Tian has got for him and the restaurant they go happens to be same restaurant his father used to own when he was a child he gets traumatizing flashbacks of his childhood and runs away. He Tian goes after him and sees him having a panic attack. At that moment Mo Guan Shan seeks He Tian for comfort, having the latter stay by his side until the end and eventually getting him home safely.
Despite his initial hostility towards He Tian, he seems to care a lot about his safety to the point that when he thought He Tian was in some kind of danger he didn't waste a second running to his house to save him, confessing he doesn't hate him that much in the process. He Tian seems to interpret this as a love confession. It all ended up being nothing but a misunderstanding.
In chapter 196, Mo Guan Shan takes an early leave of school to visit his father in prison. Here we learn that his father never allowed Mo Guan Shan to visit him before, this being the first time in years he has seen his father. Between tears he shows his resolve to become a courageous and upstanding person like his father is. Later in that day, Guan Shan recalls his childhood where he was bullied by his peers because of his family situation. In the end, he ends up getting in trouble with a mob and gets beaten up but He Tian comes in time to save him from further damage.Eventually they run away together but because of blood loss Mo Guan Shan ends up losing consciousness on He Tian's arms. Next thing he wakes up in a hospital with He Tian right beside him telling him to not worry, and that he paid all the hospital fees. For the next few day, he notices He Tian's absence and even asks Jian Yi for him. It seems that after the last events Mo Guan Shan might have started to realize he has some sort of physical attraction towards He Tian, getting to the point where he dreams about him repeatedly.
When Jian Yi, accompanied by Zhan Zheng Xi, comes to visit him at home he reluctantly lets them in. Mo Guan Shan just ignores them and seems distracted by his phone but when Jian Yi gets up and offers him a bag of money to help pay the loan, Mo Guan Shan is visibly bothered and tells him to take it back. He leaves the house to buy some drinks wondering if Jian Yi robbed a bank just then he notices a pair of shoes right in front of him. The moment he realizes those belong to He Tian and is about to say his name he is left speechless when He Tian just leans over him and put his head in the crook of his neck. Noticing something is very off with He Tian he lets him have his way.
- He is left handed.
- He is a good cook, noted by He Tian, Zhan Zheng Xi, and Jian Yi.
- His family used to own a restaurant, so that's probably why he's a good cook.
- He's seen wearing an orange bracelet in many chapters and in different illustrations.
- Official illustrations hint that He Tian and him are a couple in the future. A few of them even sometime before that.
- He Tian gave him the English nickname of "Don't Close Mountain" and "Little Mo".
- He Tian gave him a giant plush sandwich for Valentines Day.
- He is kept the Adidas jacket He Tian lent him.
- He has a very scientific Zodiac book.
- He has pierced ears and owns a pair of earrings given to him from He Tian.
- His red hair is natural, not dyed.
- He's always seen eating sandwiches.
- He likes sunflower seeds, and has stuck them to the classroom windows before using 504.
- He smokes in future chapters.
- He Tian and him are shown shotgun kissing in one of Old Xian's official illustrations and in the special Christmas chapter.
- He owns a bike and rides it home/school sometimes.
- He seems wary of needles.
- Mo Guan Shan is shown wearing a matching Cartier wedding ring with He Tian in one official illustration.
- "What is it to you? Are we suppose to be familiar?" (Mo Guan Shan to He Tian)
- "The other party is gentle, caring and understanding?… What is this nonsense?" (Mo Guan Shan to himself)
- "He Tian..." (Mo Guan Shan says He Tian's name for the first time)
- "Bro... You... aren't in love, are you?" (Mo Guan Shan's friend about him)
- "F*ck you! Youre in love! your whole families in love!" (Mo Guan to friend)
- "I was kidding earlier! He Tian! I don't actually hate you that much!" (Mo Guan Shan to He Tian)
- "...I've been doing very well... I've been taking good care of mom... I go to school on time... and I am able to make friends with the people in my school... more than anything... I will become someone courageous and upstanding like how father is..." (Mo Guan Shan to his father)
- "Where's He Tian?" (Mo Guan Shan asking Jian Yi for He Tian)
- "Dammit... I dreamed about that bastard again..." (Mo Guan Shan to himself about He Tian)
- "You... You came back..." (Mo Guan Shan to He Tian when he returns)
- "Behind the black curtains, I avoided everyone’s sight, but bumped into you." (Mo Guan Shan about He Tian)
- "Just now... you... were jerking around and screaming for help in your sleep... I was so scared that you had some weird illness and were dying..." (Mo Guan Shan to He Tian)