@Alphazet 1st, who cares if they are or aren't blood related? Look at my profile picture for that.
What I care about is HOW it's done... not if it's done...
It's like you are only focusing on the fact that we don't support the sister and not taking the context.
For crying out loud, the last page with him just showing normal care is being used to try and mean something more... that's just bad writing....
That's the problem everyone has with the imouto.... her arc isn't written well... she's just added to make this a harem.... like that's literally her only real role in this... to be a harem member and add a little extra drama
If it was done well, I don't think anyone would have minded.....
If something is done bad, it's done bad.