Ruka Igarashi is an office lady who has bad luck with men. On the 3rd anniversary with her boyfriend, she discovered that she was having an affair with him! When she collapsed in the park after getting drunk, she was rescued by Hoshikawa-san, a senior employee who was rumored to be a playboy within the company. Ruka was tired of men and declared that she would be single for the rest of her life, but Hoshikawa-san suggested to her, "Would you like to play with me?''