O-Negative
Five schoolmates who share a blood type navigate the vagaries of friendship, love and university life.
Episodes
Five students nervously await the candidate announcements of University, and are accepted into the Faculty of Fine Arts.
The students attend their first drawing class, and must attend the hazing later on. Foon and Prim are called out and must perform for everyone.
After everyone asks her whether they have class the next day, Prim creates a group-chat for them all. Puen suggests Group O because they all have the same blood type.
The students are asked to draw a landscape, without being too detailed, that reveals their feelings about the area.
The friends stay out drinking and take Chompoo home when she has too much. Only then do they realise Foon is not with them.
Puen talks to Art about his feelings for Foon, and admits to wondering whether she feels the same way about him.
The students visit an art museum and are asked to select a painting to study. Puen asks Art to work with Chompoo so that he can work with Foon.
Puen is unhappy with the way Foon acts when they are around the group. She acts differently when they are alone.
Foon reveals something to Puen that he has trouble accepting and he talks to Art about it. Chompoo's sister is about to take her own university exam.
Prim takes care of her intoxicated mother, who thinks her father is still alive. The friends are feeling lonely and have a group chat.
Art becomes jealous of Puen's easygoing manner with Prim while they are on the train. A photo in the group chat pushes Foon to make a decision.
Puen and Prim have a late night conversation when Prim can't stop worrying about her mother. She may go back after only two days.
Puen tells the group that Foon has already left, but she doesn't answer their calls. Prim confides in Puen about her mother.
Puen and Foon are caught in an embarrassing situation, but Puen manages to get them out of it. Foon's ex-boyfriend is stubborn.
Puen does not want Prim to find out about him and Foon, and Foon says she will not tell anyone. Puen goes to the pharmacy.
Foon's ex-boyfriend flies from London to surprise her for her birthday and she reminds him that she broke up with him.
Puen is torn between staying with Foon and plans he has made with Prim and her mother. Prim suspects that Puen is lying to her.
Foon is dropped off to university by her ex-boyfriend, Ong-art, surprising everyone. She reveals they are back together in the group chat.
Puen's father and mother take care of the funeral on behalf of Prim and Pook, but Prim does not show up. She has been isolating herself from her friends.
Prim comes to stay with Foon and her parents, and they tell her she is welcome as long as she likes. They will start their internships the next morning.
Art and his boss, Kwan, set up to take a landscape picture of Bangkok from her condo balcony, with no tall buildings to block the shot they can get a unique view.
Prim is working on finishing her thesis and Puen offers his help. Art's mother calls him, asking if he has decided to go to France or not.
While preparing to leave, Art shares with his class that he has dreamed of studying at this university and he has many happy memories.
Puen wonders if Prim saw him and Foon on the beach, and feels bad even though he and Foon are a couple now.
Puen apologises to Foon for making an impulsive decision, and she reveals something shocking. Puen goes to his parents for advice.
Puen waits to see Foon at hospital and Chompoo tells him that she will stay instead. Foon asks her if Prim is mad at her.
