Hormones features an ensemble cast, with nine main characters in the first season. The story mainly takes place at the fictional Nadao Bangkok College, where the characters attend upper-secondary school. All the main characters are followed throughout the season, with each episode focused on one or a few of the characters and the issues they experience.
Pachara Chirathivat as Win, the most popular boy at school who is used to getting what he wants. Later in the series he fell into the world of drugs, discothèque and night life.
Ungsumalynn Sirapatsakmetha as Kwan, a role-model student seen by her classmates as "the perfect girl". She is the smartest girl in school, but eventually she becomes stressed and deeply affected when she finds out secrets about her family.
Sutatta Udomsilp as Toei, a tomboyish and friendly girl who gets along better with male friends than with female friends. This later leads her to become labeled by her female schoolmates as a 'slut', and be nearly raped by
Elliot Jensen and Elliot Fintry have a lot in common. They share the same name, the same house, the same school, oh and they hate each other but, as they will quickly learn, there is a fine line between love and hate.