Ruga Aldica, a young man who has trained relentlessly to become a holy knight, graduates at the top of his class from the training academy and is assigned to the Sixth Order of the Holy Knights. He immediately receives the position of deputy captain due to his academic achievements, but he also learns that this division has a notorious reputation for crushing the spirits of rookies who have come before him. Preparing himself for a harsh trial, Ruga goes to meet his new commander and finds himself welcomed by Lyon Mairi, the busty captain of the Sixth Division whose chest rivals her face in size. To his surprise, Ruga discovers that he is the only male knight in the entire unit, surrounded by Lyon and other beautiful female knights.

The story takes place in a fantasy world where the Holy Knights serve as humanitys key line of defense against the Demon Kings army. Ruga harbors a sincere and earnest desire to become a true holy knight, but his resolve is constantly tested by the daily distractions posed by his female colleagues, particularly the overwhelming physical presence of his commander. His journey involves balancing his duties as a knight, maintaining his purity and discipline, and navigating the comedic and ecchi situations that arise from being the sole man in a division of women who are not shy about their appearances or their interest in him.

The main characters include Ruga Aldica, the determined but easily flustered protagonist who struggles to keep his mind pure. Lyon Mairi is the captain of the Sixth Division, a beautiful and buxom leader who welcomes Ruga warmly and becomes the primary object of his internal conflict. Other members of the Sixth Order include Madoka, a tall and slender junior knight who was given the nickname monster in her hometown due to her height and the early loss of her mother. The squad also features Karla and other female knights who each bring their own dynamics to the team, contributing to the harem-like atmosphere that Ruga must endure.

One notable narrative arc involves Ruga receiving a significant mission from the Holy Maiden after his achievements gain recognition within the Holy Knights. He is tasked with infiltrating a red-light district overrun by succubi, known as淫夢魔族, in order to conduct an undercover investigation. This mission presents the greatest threat yet to his chastity, as he must navigate a brothel filled with demonic temptresses while keeping a promise to his beloved commander Lyon regarding abstinence. The arc combines elements of comedy, ecchi, and action as Ruga uses disguises and his skills to survive the high-difficulty assignment without losing his purity.

Throughout the series, Ruga struggles with his own hesitancy and cowardice, often being called a coward by readers and characters alike for his inability to take decisive action with the women around him. Despite his perceived weakness, he demonstrates moments of strength and cleverness, using his abilities to overcome challenges while maintaining the pure heart required of a holy knight, even as the story questions whether a holy knight truly needs to remain completely chaste. The narrative balances slapstick comedy, light battle sequences, and ecchi humor as Ruga attempts to fulfill his duties without succumbing to the temptations that surround him daily.