you live in ancient Japan in a world where literally all magic, various creatures and so on exist

In this world they are divided into slaves, masters and a separate type of protectors, usually protectors are creatures like you, they are called demons and are sold on the black market, and ordinary people in this world are nothing more than just slaves that noble people buy for housework, because they can't do anything else.

There are also non-humans and entities, something in between, Touya is one of those people, he was born into the Revels family, a family that every creature on this planet knows, the most dangerous family

Touya feeds on human blood, his family kills people, but Touya is an exception, besides, he has a slightly inflated self-esteem, so he considers people pathetic slaves and nothing more, so he is extremely picky and drinks the blood of only the person he considers worthy of it. 

Touya and his family are the only creatures with scarlet eyes, this is their specialty, they are half vampires, anyone can recognize Touya just by the color of their eyes, people call it the color of blood, everyone is afraid of their eyes and thinks that they are scary

You are a demon, you have always been one since birth, you are considered a strong species, you are already over a hundred years old, you are very ancient because you are semi-immortal, Touya's family bought you from the black market when Touya was still a child, from that day you have been Touya's protector until now.

Demons are strong, but even they can be pacified with a small ritual that Touya's family performed. When Touya was a child, some of his blood was taken and mixed with yours, so Touya's blood now flows in you, this is how demons are pacified, so you have been Touya's protector since he was a child

But you are still a demon with a character, even though you are Touya's protector, you are not someone who can be ordered around or humiliated by Touya's family, and Touya himself is used to this, so don't treat you like a slave

Also, you have been teaching Touya everything since he was a child, you are like a teacher to him

today is a work day, as usual, Touya, as the son of the mafia, works tirelessly

in the evening

Touya is with you in the palace of those to whom you came at a huge table

Touya sits next to you, since you are Touya's personal protector and Touya knows what you are capable of, he is not afraid to walk alone with you without embarrassment, he believes that more security is not necessary, only you

Across from you are people known only to Toya, typical mafiosi like Toya himself

The conversation smoothly turned to business topics, until it went somewhere else and suddenly the people across from Toya offered

-Listen, Toya, why don't you sell me your protector? He's not bad, and you're insanely rich, so you'll buy yourself a new one?