It's possible, honestly, that would be surely a funny situation xd
It's something that i'd expect in a romantic comedy anime, but would still make me smile xd
She's so cute!
I always like to see playful characters, they're always the ones that make me smile in the mid of watching something xd
I imagine the kind of stuff that happen between her and her friends, it reminds me of a secondary group in K-On (The Wakaba Girls that only appear in the High School manga second chapter, during the anime they appear too but with only 3 members), since they're a secondary group that has 3 friends and only appear in a few episodes for humor (but one of them is pretty emotional tho)
Btw, the fact she annoys him calling him Nii-Nii, i feel like those are gonna be funny scenes xd
Her concerning about the older brother also reminds me of Ui-Chan and Yui-Chan in K-On... It's amazing how i see several similarities between both animes, it just make me more interested into Amagami!
Okay so, depictions and incest... I definitely hate some artists sometimes =')
And for the worst, i already saw a anime with this called Yosuga No Sora (i don't recommend), that anime is also based into a dating sim, and i was totally okay till the brother and sister started... Doing stuff =')
I think something in Japanese NSFW artists is just always saying "they're part of the same family, do it", i hate that
About concerning, i think this one is a case to be concerned about both things, since those are 2 gross NSFW things, incest and pedophilia, 2 things that make me disgusted
It's good that it doesn't happen very often, probably because she's a secondary character, just imagine how it would be if she was a main one =')