Keiki Kiryu is a kind-hearted high school student surrounded by attractive girls. One day, he finds a love letter with no sender information, other than a pair of panties. Keiki begins his investigation by speaking to his senpai, Sayuki.

Keiki's investigation reveals that the senpai he looks up to is a huge pervert, but it doesn't stop him from pushing forward. There are other suspects to interrogate! He approaches his kohai Yuika, a cute and supportive student librarian.

In addition to shaking his world-view, Keiki's encounters with the abnormal have led him to conclude that neither Sayuki nor Yuika are the elusive Cinderella. Through process of elimination, the only one remaining is Mao.

Keiki continues to receive mixed messages from Mao. Could she be the elusive Cinderella, or is she in love with someone else? Keiki decides that he must confront Mao directly to find out.

Keiki's search for someone who truly loves him, not as the object of a perverted fantasy, hits another dead end. However, another unsigned letter grabs his attention, although this time, it's blackmail.

Keiki works with Koharu to help her win Shoma's heart, but Keiki's attention is diverted by another Cinderella suspect - student council vice-chairperson Ayano Fujimoto. Could she be the one, true, non-perverted secret crush?