"Seito Kaichō Hikaru" centers around Hikaru Midorikawa, a high school student who unexpectedly becomes the student council president after winning the election by a landslide. Despite her lack of experience and initial reluctance, Hikaru steps into the role with determination, aiming to bring positive change to her school. Her leadership style is unconventional, often driven by her strong sense of justice and desire to help others, even if it means challenging established norms.

The series explores the dynamics within the student council, which includes a diverse group of characters with distinct personalities and roles. Among them is Aoi Saionji, the vice president, who is pragmatic and often serves as a counterbalance to Hikaru's idealistic approach. The council also includes other members such as the diligent secretary, the mischievous treasurer, and the quiet but observant public relations officer. Together, they navigate various school-related issues, from resolving conflicts among students to organizing events and addressing administrative challenges.

Hikaru's journey is marked by her growth as a leader and her ability to inspire those around her. Her interactions with the student body and the council members highlight themes of teamwork, responsibility, and the importance of understanding different perspectives. The narrative often balances lighthearted moments with more serious situations, reflecting the complexities of high school life and the responsibilities of leadership.

Throughout the series, Hikaru faces numerous obstacles, including opposition from those who doubt her capabilities and internal struggles with self-doubt. However, her unwavering commitment to her ideals and her willingness to learn from her mistakes drive her forward. The story also delves into the personal lives of the supporting characters, providing depth to their motivations and relationships.

"Seito Kaichō Hikaru" presents a blend of comedy, drama, and slice-of-life elements, offering a portrayal of the challenges and rewards of leadership in a school setting. The series emphasizes the importance of perseverance, empathy, and collaboration, making it a relatable and engaging narrative for viewers interested in stories about personal growth and community.