[Black Butler] A Secret Ledger for Two

A younger brother can only rely on his older brother for his whole life.

Isn't that only natural?

[I'm putting this story on hold for now. I'll revisit the plot when I have time.]

There may be some out-of-character moments. I haven't finished Black Butler, and the author made up the setting.

Theme: An older brother protecting his younger brother is only natural.