Fujigaya Hiro is a male high school student with an unwavering dream: to become the kind of heroic lead found in a shoujo manga. Every day, he rides the same train as Hoshikawa Yuai, a girl from the prestigious Sumeragi Girls' Academy, and secretly makes a habit of catching glimpses of her, harboring a crush. His aspiration is to one day protect her from danger, sweeping in to save her like a classic shoujo hero. However, reality is far from his fantasy. His childhood friend, Yamanouchi Saku, an effortlessly handsome and popular boy, often listens to Hiro's ambitions with a mixture of amusement and exasperation.

The dynamic of Hiro's world is turned upside down during a crowded commute. Hiro finds himself trapped next to a molester on the train. Frozen and unable to even raise his voice, he is on the verge of tears when a girl's deep, commanding voice cuts through the carriage. It is Yuai, who effortlessly subdues the molester with wrestling moves and drives him off. In that moment, Yuai becomes the protector, smiling and extending a hand to a dazed and disappointed Hiro. The roles are completely reversed; the girl he wanted to save has instead saved him.

Complicating matters further, Hiro remains completely oblivious to the fact that his childhood friend, Saku, has developed intense, one-sided romantic feelings for him. Saku's affection manifests in possessive and clingy behavior, placing Hiro at the center of a lopsided love triangle he does not even realize exists. As the story progresses, Hiro tries to navigate his growing closeness with Yuai while being unwittingly pursued by Saku. The narrative expands beyond the initial triangle when Yuai's younger brother, Yuuzuna, enters the picture, developing his own feelings and even resorting to cross-dressing to get closer to Saku, escalating the situation into a four-way romantic entanglement.

The central conflict revolves around Hiro's persistent but comically thwarted desire to be a strong, protective hero, even as he is consistently placed in the role of the one being protected, pursued, and doted upon by both his crush and his childhood friend. Character development primarily focuses on Hiro gradually becoming aware of Saku's feelings and the shifting nature of his own heart, while Saku struggles with the intensity of his emotions and the risk of confessing. The setting remains centered on their daily school lives, train commutes, and social circles, providing a familiar backdrop for the evolving romantic comedy and the exploration of identity, gender role reversal in relationships, and the messy, often humorous, nature of young love.