Now mind you... being a demon I sort of have to support anything that tempts people to the taste of forbidden fruit. Thusly I gave this one a rather undeserved 2 when really it's probably a 1... maybe less.
I'm all for the brother loves sister, (or in much more interesting cases Sister loves Sister;) but really this anime was missing too many things to make it worth while. The characters MIGHT have been more interesting if I knew more about them, how they got where they are, what their hobbies and habits were, or anything that would actually make me give a crap about these two.
The back story on said hero and heroin however is MIA, nothing is mentioned about who their friends are how they met, what tribulations they went though to reach such a close relationship, NOTHING, NADA, ZIP. As a result I couldn't care less about the two main characters and kept hoping that at any moment some large flesh eating bird would swoop down and devour the lot of them! Ahh now that's entertainment.
To top it off there is absolutely nothing special about either of our main brother/sister combo, neither one is a Demon lord, angel, alien, robot, super-powered extra-dimensional being, vampire, werewolf, deity or really ANYTHING that would spice things up, and boredom set in almost right off the bat.
To Galadrel who gave this a 7.8.. too generous my friend, much too generous. Don't call a pile of crap a rose, people might try to smell it.