Winter Fuyuumi has carried a childhood promise with her since kindergarten. She was once engaged to a boy she called Takkun, and though she moved away ten years ago, she never forgot him. Now enrolled at Hane-no-Yama High School, Ai finally reunites with that boy, Eita Kidou. The problem is that Eita does not remember her at all.

This manga is a spin-off centered entirely on Ai Fuyuumi, one of the heroines from the Ore no Kanojo to Osananajimi ga Shuraba Sugiru series. It delves into her backstory, tracing how she first met Eita as a child, how she fell in love with him, and what happened during the years they were apart. The story also revisits key events from the main series through Ai's own perspective, showing her thoughts and emotions during moments that were previously shown only from Eita's point of view.

The setting is the same as the main series: Hane-no-Yama High School, where Ai serves as a strict member of the disciplinary committee. Her official role in the school is to enforce rules, but her real mission is far more personal. She wants to reclaim the bond she once shared with Eita. However, she finds herself competing with a growing circle of rivals for his attention. Eita is caught in a fake relationship with Masuzu Natsukawa, the school beauty who despises romance but uses him as a decoy boyfriend. His childhood friend Chiwa Harusaki openly loves him and refuses to back down. The mysterious Himeka Akishino also inserts herself into the fray, claiming to be his ex-girlfriend.

The narrative arcs in this spin-off focus heavily on Ai's internal world. It shows her early childhood with Eita, the moment she fell for him, and the pain of separation. After her return, the story follows her determined but often clumsy attempts to rekindle that connection, even as the romantic chaos around Eita escalates. She joins the so-called Jien Otsu club, a group dedicated to supporting Eita, which becomes a front for the girls competing for his heart. The manga also explores her complicated home life and her strict, sometimes tsundere personality, showing the vulnerability beneath her disciplined exterior. Ultimately, it is a character-driven exploration of Ai's love, her memories, and her struggle to make Eita remember the promise they once made.