Shoko Aizawa is a supporting character in The Garden of Words. She is a popular high school senior who attends the same school as the protagonist, Takao Akizuki. Aizawa is known for her striking appearance and high pride, and she is almost always seen in the company of her close friends, who act as her followers.

Her background is more complex than it first appears. Before her transformation in the final year of junior high school, Aizawa was considered unattractive and was frequently disliked by boys, having only a small circle of friends. After making a conscious effort to change her appearance, including losing weight and altering her style, she became a beautiful and attention-grabbing student. This drastic change in her social standing informs much of her personality and actions.

Aizawa’s personality is defined by her pride and a seemingly callous exterior. In the film, she is depicted as the primary antagonist who instigates a bullying campaign against her homeroom teacher, Yukari Yukino. She spreads rumors about Yukino, ultimately forcing the teacher to quit her job. When confronted about the harm she has caused, Aizawa shows no remorse, displaying a shocking level of insensitivity. Her motivations stem from a place of jealousy. She began dating a handsome older student named Shinji Makino. However, when she discovered that Makino was attempting to flirt with Yukino, her initial admiration for the teacher turned to intense resentment, leading her to orchestrate the campaign of harassment.

The novelization of the story provides a deeper look into Aizawa's inner world, revealing a more tragic and nuanced character. It shows that her bullying was not purely malicious but also a manifestation of her own insecurities and pain. Her home life was troubled, marked by her father's extramarital affair and a distant relationship with her older brother. She was raised without a consistent maternal figure and felt pressured by a society that values appearances, which contributed to her desperate need for social validation. After being dumped by Makino, she channeled her hurt and anger into tormenting Yukino. In the novel, after Yukino is forced to leave the school, Aizawa is so overwhelmed by the consequences of her actions that she vomits and later lives with significant guilt over what she has done.

In the story, Aizawa serves as a major obstacle and a source of conflict. Her actions are the direct cause of Yukari Yukino's emotional distress, which led the teacher to spend her lonely mornings in the park where she meets Takao. Aizawa’s role culminates when Takao, having learned the truth about Yukino’s situation, confronts her in the school hallway. In response to Aizawa’s continued insults towards the teacher, Takao slaps her, an act for which he is then beaten by her friends. This confrontation is a key turning point that pushes Takao to seek out Yukino and express his feelings.

Regarding her abilities, Aizawa has no physical or supernatural powers. Her most notable ability is her social influence. She is a skilled manipulator who successfully turns her classmates against a teacher and manages to evade any serious consequences for her bullying, largely due to the school's concern for its own reputation.