As Kobayashi prepares to go for work, she opens her apartment door to see an extraordinarily terrifying sight—the head of a dragon glaring at her from across the balcony. The dragon instantly turns into a pretty, busty, and lively young lady clothed in a maid uniform and introduces herself as Tooru. The stoic programmer had seen the dragon the night before on a drunken expedition to the mountains, and because the mythological beast had nowhere else to stay, she had offered the creature a place to stay in her home. Tooru had so came to take advantage of the opportunity, eager to reciprocate her savior's goodwill by working as her personal maidservant. Despite being terribly sorry of her words and hesitant to follow through on her promise, a mix of guilt and Tooru's incredible dragon abilities convinces Kobayashi to take the girl in.