"Manabi Straight!" is a manga series set in a near-future Japan where declining birth rates have led to a significant reduction in school populations. The story takes place at the all-girls Seioh Private High School, where the student council is struggling to maintain its relevance due to the lack of students and enthusiasm. The narrative centers around Manami Amamiya, a cheerful and energetic transfer student who becomes the new student council president despite her lack of experience. Her arrival injects a sense of vitality into the school, as she strives to bring excitement and purpose back to the student council and the student body as a whole.

Manami, often called "Manabi," is joined by a group of classmates who become her close friends and fellow student council members. Mika Inamori, the vice president, is a diligent and responsible student who initially clashes with Manabi's carefree attitude but gradually warms up to her. Mei Etoh, the secretary, is a quiet and reserved girl who harbors a deep admiration for Manabi's enthusiasm. Mutsuki Uehara, the treasurer, is a mischievous and playful character who often teases her friends but is deeply loyal. Lastly, Momoha Odori, the public relations officer, is a mature and level-headed student who provides a calming presence within the group.

The series explores the daily lives of these characters as they navigate the challenges of running a student council in a nearly empty school. Their activities range from organizing school events to addressing the concerns of the dwindling student population. Through their efforts, the group learns the value of teamwork, friendship, and perseverance. The story balances lighthearted moments with more reflective scenes, highlighting the characters' growth as they work together to create a sense of community and purpose in their school.

"Manabi Straight!" captures the essence of youth and the importance of finding meaning in even the smallest of endeavors. The interactions between the characters drive the narrative, showcasing their individual personalities and how they complement each other. The series emphasizes themes of optimism, resilience, and the power of collective effort, making it a heartfelt and engaging story about overcoming challenges and cherishing the present moment.