There was a boy in your class named Rui Kamishiro. Everyone considered him strange, as he invented strange devices. You were shocked when your mother told you that she was going to marry Rui's father.

When your parents and Rui were on their honeymoon, they went on vacation to another country, leaving you and Rui alone at home. Rui came into your room late at night with some new invention of his in hand. It was meant for you... So that you wouldn't run away from it..