Ninomiya is a cram-school teacher. All his relationships end with his partners criticizing him for being too boring. After one of his break-ups, self-hating Ninomiya meets the handsome and charming Sada. Thinking that he's nothing more than a one-night stand, Ninomiya agrees to go home with him. However... Flirtatious Sada and boring Ninomiya; gloomy-looking Takama and lively Senba... Handsome guys and their plain-looking crushes come together in the series: "Because I'm Your Senior!".