"Fudanshi Shōkan: Isekai de Shinjū ni Hameraremashita" is a manga series that blends elements of fantasy, comedy, and yaoi themes. The protagonist, a fudanshi (a male fan of boys' love content), is unexpectedly summoned to a fantasy world. Upon arrival, he discovers that the world operates under a unique system where individuals are bound to their soulmates through magical collars. These collars, known as "shinjū," ensure that the wearers remain together, often in romantic or intimate relationships.

The protagonist is paired with a powerful and stoic demon lord, creating an immediate dynamic of tension and humor. The demon lord, initially resistant to the bond, gradually develops a complex relationship with the protagonist as they navigate the challenges of their forced partnership. The story explores their interactions, blending comedic moments with deeper emotional undertones as they confront external threats and internal conflicts.

Supporting characters include a variety of magical beings and other summoned individuals, each with their own shinjū bonds, adding layers to the world-building and interpersonal dynamics. The narrative delves into themes of fate, consent, and the nature of relationships, often using humor to balance the more serious elements. The protagonist's fudanshi tendencies frequently influence his perspective, providing a unique lens through which the story unfolds.

The plot progresses as the protagonist and the demon lord work together to uncover the mysteries of the shinjū system and the reasons behind the protagonist's summoning. Their journey is marked by battles, political intrigue, and moments of introspection, all while their bond continues to evolve. The manga maintains a lighthearted tone despite its fantastical and occasionally dramatic elements, making it an engaging read for fans of the genre.