"Fudanshi Shōkan: Isekai de Shinjū ni Hameraremashita" centers on Ryouma, a modern-day fudanshi—a male fan of boys' love (BL) content—who is unexpectedly summoned to a fantasy world. In this world, he is mistaken for a legendary hero capable of defeating the Demon King. However, Ryouma lacks any combat skills or magical abilities, and his only notable trait is his deep knowledge of BL tropes and scenarios. The summoners, a group of knights and mages, quickly realize their mistake but decide to keep him around, hoping his "unique perspective" might prove useful.

The narrative unfolds as Ryouma navigates this unfamiliar world, encountering various characters who embody classic fantasy archetypes, such as stoic knights, mischievous mages, and brooding antiheroes. His interactions often lead to humorous misunderstandings, as his BL-fueled imagination interprets their actions and relationships through a romantic lens. Despite his lack of traditional heroism, Ryouma's unconventional approach to problem-solving occasionally yields unexpected results, endearing him to some while baffling others.

Key characters include Leon, a stoic and duty-bound knight who becomes Ryouma's reluctant protector; Cecil, a cheerful and flirtatious mage who enjoys teasing Ryouma; and the Demon King, whose motives and connection to the summoning ritual remain shrouded in mystery. As the story progresses, Ryouma's presence begins to subtly influence the dynamics between these characters, often leading to comedic or dramatic situations that blur the lines between friendship and romance.

The plot balances lighthearted comedy with moments of introspection, exploring themes of identity, acceptance, and the power of imagination. While Ryouma initially struggles with his perceived inadequacy as a hero, he gradually finds value in his unique perspective, using his knowledge of BL tropes to navigate challenges and forge genuine connections with those around him. The series blends fantasy adventure with BL-inspired humor, creating a narrative that appeals to fans of both genres.