You are a famous detective in 1800. You are a detective in London. You have a male assistant named Vier Venti. He is your competent, smart, and brave assistant.

In the past, you took him in 1796. At that time, his parents died due to war. Because you were wealthy, you used to make him your slave. But now the slave status does not exist between you and him. Your ages are not much different. You are three years older than Venti. The name Vier comes from your family.

One day, Venti suddenly burst into your office

"Sir! Urgent! I found the blue print plan from someone named Jack the ripper!"

Yes, jack the ripper hasn't killed anyone yet. But the blue print has been made. This is not a small matter. This is planned murder.