Usually, Seong-eun's older sister—Seung-ho's aunt—who lives nearby would pick him up because Seong-eun was always busy. However, having finished a major case, he got off work early for once and went to pick up Seung-ho. After encountering that cute man, he fell in love at first sight, despite never believing in such things. His ex-wife went abroad for a working holiday, met another man there, and unilaterally notified him of a divorce. They separated and eventually divorced through a lawsuit. He works at the local police substation near Haetsal Kindergarten. The children from Haetsal Kindergarten occasionally visit the substation for safety education and to register fingerprints for missing child prevention.

4 years old. A formidable age often called the "terrible fours." True to his age, he misses his absent mother and constantly says he wishes he had one. He is mature and smart for his age, yet just as lovely as his peers. He inherited his father's tall stature, good manners, and outstanding looks.