Kyotaro Ichikawa, a deeply self-conscious middle school boy with a flair for the macabre, spends his days in the school library reading a murder encyclopedia and nurturing dark fantasies about eliminating his popular, cheerful classmates. His primary target is Anna Yamada, the class idol and a tall, beautiful magazine model whose very presence seems to represent everything he resents. However, Kyotaro’s murderous delusions begin to crumble when he observes Anna in private. He discovers that beneath her perfect exterior, she is surprisingly quirky, often sneaking sweets into the library and displaying a clumsy, endearing side. As they repeatedly find themselves alone together, sharing snacks and quiet conversations, his fantasies of killing her transform into the unfamiliar and terrifying pangs of first love.

The story primarily unfolds within the halls of their middle school and the library, a quiet sanctuary where these two opposites gradually dismantle each other's facades. Kyotaro, who is actually perceptive but plagued by low self-esteem, begins to see Anna not as an idol but as a normal, considerate girl who cries easily and gets jealous. Anna, in turn, is drawn to Kyotaro’s unexpected kindness and maturity. The narrative charts their awkward, tentative steps toward each other, navigating school festivals, class trips, and the antics of their friends, including the gyaru Moeko Sekine, the oblivious Chihiro Kobayashi, and the blunt Serina Yoshida. The light novel shifts focus away from Kyotaro’s usual internal monologue to present a series of four brand-new side stories, offering fresh perspectives on the central romance.

One story explores the relationship between Kyotaro and Anna through the watchful eyes of their friend Moeko, who is determined to support them from the sidelines. Another follows the fallout of a double date, focusing on Kenta Kanzaki and his budding romance with Honoka Hara. A separate narrative delves into Kyotaro’s past, revealing the curious lore behind a rare trading card he received in elementary school from a mysterious woman, a secret that resurfaces when he runs into Anna on his way to sell it. The final major arc centers on a visit to the Yamada household, where Anna’s tipsy mother unintentionally recounts the secret story of her own relationship with Anna’s father, much to the young couple’s embarrassment. The collection is also hinted to include an epilogue that peers a decade into the future, showing where the characters end up.