The creature known as man is quick to misunderstand. The same applies to the the pure middle-schooler Yokoyama: a diligent fellow who does his infirmary duty properly.

Few nice words from his classmate, Nishino, end up being a driving force behind Yokoyama's imagination running wild making him believe that she's only nice to him.

This is the start of the misleading life between the fantasizing Yokoyama and the equivocator Nishino.