"Dokyū Hentai HxEros" is a science-fiction comedy anime set in a world where humanity faces an alien threat known as the Kiseichū, insect-like creatures that feed on human sexual energy, referred to as H-energy. To combat this invasion, the HxEros organization deploys special heroes equipped with advanced technology called HxEro Gear, which amplifies their H-energy to fight the Kiseichū. The story centers on Retto Enjō, a high school student who becomes a member of this team after a childhood encounter with a Kiseichū leaves him determined to protect humanity.

Retto joins forces with Kirara Hoshino, his childhood friend and a fellow HxEros member, who harbors feelings for him. The team also includes Momoka Momozono, a skilled hacker with a sharp tongue; Sora Tenkūji, a reserved and intelligent girl with a mysterious past; and Chacha Akatsuki, a cheerful and energetic member who brings levity to the group. Together, they work to defend Earth from the Kiseichū while navigating the challenges of their personal lives and relationships.

The narrative explores the dynamics between the team members as they balance their heroic duties with their everyday lives. The Kiseichū attacks often involve bizarre and comedic scenarios, as the aliens exploit human desires and emotions to drain H-energy. The HxEros team must confront these threats using their unique abilities and teamwork, often leading to humorous and action-packed encounters. The series blends elements of ecchi comedy with moments of character development, particularly focusing on Retto and Kirara's evolving relationship and their shared history.

As the story progresses, the team uncovers more about the Kiseichū's origins and their connection to humanity. The series delves into themes of courage, friendship, and the complexities of human emotions, all while maintaining a lighthearted and comedic tone. The interplay between the characters and their growth as individuals and as a team forms the core of the narrative, set against the backdrop of their ongoing battle against the alien threat.