From Kirei Cake:

Youko is a nursery school teacher who is searching for her long-lost "first love" that she had when she was five years old, and the only clue she has to finding him is a small figurine given to her before they were separated.

Detective Higurashi Tabito has the uncanny ability to "see" through all of his senses. Using this ability, he focuses on the one thing he is best at doing: Searching for lost items. Unfortunately, his life takes a complete turn when one day, he finds out that Youko has the same figurine that he has!

With Youko being in her prime and Tabito being an eccentric, this is the story of Youko's search for "him," and Tabito's search for "her!"