High school second-year Soujiro Sakagami is late for school one day, when he is given a ride by a mysterious girl who looks like a third-year, and claims that her fortunes are 100% accurate. She declares that he is fated to be with a girl younger than him... but little does he know that she's referring to herself! So begins a comedy of love between the fumbling Mizuki-"senpai" and clueless Sakagami!