Natsunoko Mamiya is a single woman of 28 years. Being surrounded by male colleagues in her workplace, she seeks solace in the peaceful smoking area located at the back of the building. On one occasion, she encounters a new co-worker by the name of Hisaya Takao in the same area, who requests a light for his cigarette. As she prepares to lend him her lighter, their cigarette tips touch in a momentary "cigarette kiss". Following this encounter, they begin to frequent the smoking area together and develop a close bond. Despite being Natsunoko's junior in the company and younger than her, she cannot ignore the growing affection within her, which ignites like a cigarette.
