Yeah, she was already shown in Magic Ring game so used her design to make Ruby to show all of people in her family has same hairstyle and look. Just as a joke. Emerald looks different since she her family does different work.
Buff's effect will depend on the girl. Best healing is achieve with Junsa and best strengh buff with Himawari. If you want best of both world Aoi Karasuyama is your choice. Most interesting buff would with Nadeko but since there are cheats in the game it will make them useless.
It's not special though. I'm focused more on the character not the background.
That image was edited to not make her Ai with Kunio. Her hairs will remain same for Magic Ring.






