"So I Can't Play H" centers around Ryouichi Kaga, a high school student who inadvertently becomes the familiar of Lisara Restall, a demon girl from the demon world. The story begins when Ryouichi accidentally summons Lisara while attempting to perform a ritual to rid himself of his bad luck with women. As a result, Ryouichi is bound to Lisara as her master, and their lives become intertwined. However, their relationship is complicated by the fact that Lisara is a "H-demon," a type of demon that thrives on sexual energy. This creates a unique dynamic, as Ryouichi must navigate his growing feelings for Lisara while dealing with the consequences of their bond.

The narrative explores the challenges Ryouichi faces as he tries to maintain a normal life while fulfilling his role as Lisara's master. Their bond requires Ryouichi to provide Lisara with sexual energy, which often leads to comedic and awkward situations. Despite the humorous tone, the story also delves into the emotional struggles of both characters. Lisara, though initially aloof and focused on her duties, begins to develop genuine feelings for Ryouichi, while Ryouichi grapples with his own insecurities and the complexities of their relationship.

The series introduces additional characters who add depth to the story. These include Nanami, Ryouichi's childhood friend who harbors feelings for him, and Myuu, another demon who becomes involved in their lives. The interactions between these characters create a blend of comedy, romance, and supernatural elements. The plot progresses as Ryouichi and Lisara face various challenges, including encounters with other demons and the need to protect their bond from external threats.

The anime balances lighthearted moments with themes of trust, loyalty, and personal growth. The relationship between Ryouichi and Lisara evolves as they learn to rely on each other and confront their own vulnerabilities. The series concludes with a resolution that ties together the central conflicts while leaving room for the characters' continued development. Overall, "So I Can't Play H" combines supernatural intrigue, romantic tension, and comedic elements to create a narrative that explores the complexities of human-demon relationships.