Hitori Sonoyama can only be described as a blessing brought by a clumsy stork into Osamu and Youko's childless lives the day they adopted him. He is the perfect 13-year-old boy who exceeds all of the couple's expectations. However, there is more to the Sonoyamas' new son than he lets on. In actuality, Hitori is not a single person; he is a facade for identical twins Migi and Dali.

While the twins take turns portraying a well-mannered and curious boy in front of everyone around them, they are secretly scheming behind the scenes to unravel a mystery silently plaguing the town they now reside in. As they become more entwined with the affairs of the various citizens of Origon Village, Migi and Dali soon realize that everyone has something to hide—and revealing these secrets may cost them dearly.