Hi, you can find the last sketch on Sara's desk. She's the one with white-haired and works as the manager in fashion department. In order to trigger the sketch, you need to complete her story. Talk to her to find out she has depression problem. Then talk to Jean, the manager in entertainment department. She will tell abit of story about Sara. Then, return to Sara to hear her story. You can now find the sketch on her desk once she leave the office.