(A lil spoiler)
Aoi asks her how to make his girlfriend feel good (there's no girlfriend here, he loves Iori) then they "practice" with each other. She freaks out how much she enjoys that because they are siblings, the fact is they aren't, only Aoi and the parents know that. He keeps pushing her to have sex so... if forced sex is not your thing then please skip this. Later, you will know why she keeps being in a relationship even with people she doesn't like and also her true feeling towards her brother.
She's kinda slutty lmao so it personally makes me mad and feel bad for Aoi.
When he finally tells him that she's adopted, her answer is so 🤬🤬🤬🤬. The ending is unsatisfying omg!!! Beside that, to me, everything else from art style, their facial expressions to the sex scene is really good. The story is well written, except the ending. Worth reading.