"My Stepsister Tries to Hypnotize Me" centers on the relationship between two step-siblings, Yuu and Akane, whose lives take an unexpected turn when Akane begins experimenting with hypnosis. Yuu, a high school student, finds himself living with Akane after their parents remarry. Initially, their relationship is distant and awkward, but Akane, who is deeply interested in psychology and hypnosis, decides to use her skills to manipulate Yuu’s behavior. She claims her intentions are to improve their sibling bond, but her methods blur the lines between playful experimentation and emotional manipulation.

As the story progresses, Akane’s hypnosis attempts become more frequent and intense, leading to a series of comedic and dramatic situations. Yuu, though initially resistant, begins to question whether Akane’s actions are entirely self-serving or if she genuinely cares about their relationship. The narrative explores themes of trust, boundaries, and the complexities of blended family dynamics, as Yuu struggles to navigate his feelings toward Akane and her increasingly unpredictable behavior.

The manga balances humor with moments of tension, as Akane’s hypnosis experiments often lead to misunderstandings and awkward scenarios. Supporting characters, including friends and classmates, occasionally become involved, adding layers to the story and highlighting the impact of Akane’s actions on Yuu’s social life. The dynamic between the two protagonists evolves over time, with Akane’s motivations and Yuu’s reactions driving the plot forward. The series maintains a lighthearted tone while delving into the psychological and emotional implications of Akane’s hypnosis, creating a unique blend of comedy and drama.