Kobayashi is a computer programmer and office worker. She finds herself living with a dragon named Tohru.

Even though Kobayashi maintains a cool demeanor, she has been regarded as kind-hearted and reliable among her friends and colleagues. Level-headed and pragmatic, she stands as the source of reason when dealing with her dragon friends. However, when intoxicated, she tends to become rowdy and aggressive, especially in her interests in maids, and is not above subjecting Tohru to her drunken whims.

Before meeting Tohru, Kobayashi would don a stoic expression on her face. Now, she is more approachable and open to others, often seen smiling contentedly. Kobayashi often chastised Tohru for her lack of propriety on human standards. However, as time passes by, she grows accustomed to Tohru's quirks and would sometimes show small signs of affection and gratitude for the dragon, such as holding Tohru's hand or going out of her way to fulfill some of Tohru's wishes to ease her troubles.