Implied in multiple episodes, Oh Baek-Ryeon is stated to be a orphan and grew up in an orphanage. It is never confirmed what happened to her biological parents
Most Episodes feature scenes in a veterinary clinic, as the female lead is a Vet. Additionally, several episodes feature scenes of a person receiving and recovering from a major head surgery in a hospital.
End of episode 4 a development in the case is made after the policeman and a woman enter an apartment. There is blood on the floor. It is visible in the opening of e5 as well