After finally adopting a child, the Sonoyamas were unprepared for the mystery that would soon unravel. Hitori seems to be the perfect son for his lovi…
The twin boys Migi and Dali live in an orphanage until one day they are adopted by a wealthy and gentle elderly couple, the Sonoyamas. However, they are not taken in as the two boys 'Migi' and 'Dali,' but rather as a single boy named 'Hitori Sonoyama.'
Migi and Dali have been fully accepted as members of the Sonoyama family, but they notice that Mom and Dad are acting somewhat distant. Suspecting that the couple might be hiding something, the two begin searching the house and stumble upon a secret.
To uncover the truth behind their mother's death, Migi and Dali finally begin to take serious action. Their clue is the memory of the room they lived in with their mother when they were young. In order to locate the room, the twins come up with a plan.
Migi and Dali begin attending school to befriend Eiji, the son of the Ichijo family. However, to get close to Eiji, they need to join a top class. The two start studying to boost their grades, but Migi falls head over heels for a certain female student.
After Hitori achieves first place in a test, the Sonoyama family is invited to the suspicious Ichijo household. Seizing the opportunity, Dali thoroughly explores the Ichijo house. However, they fall into Eiji's trap, resulting in Migi being captured.
Dali continues investigating the Ichijo family while Migi plays the role of a perfect toddler. He successfully keeps up the act, but as the conditioning program is suddenly ended, they have to return to the Sonoyama house.
