defective condom's feed

It's a historical, supernatural manga taken place in Japan. The main character is a demon hunter or something.

The main character is a boy, black hair and empty eyes. He has a "little brother" that follows him and he takes care of. I guess it's just the two of them but the brother isn't actually his brother, it's a demon he probably made a pact with ig.

The cover should be a boy and a red background, thanks (｀_´)ゞ