In Akaneiro ni Somaru Saku, the “route that makes the most sense” according to Eclipse’s translator is the one with your biological sister. In the anime, this said sister is voiced by super popular Hirano Aya. So basically the appeal of the Akaneiro anime is incest with Hirano Aya.
I have decided that the appeal of Toradora is actually incest too. And no, I don’t mean Ryuuji’s mom. The main dynamic of the show seems to come from the relationship between Ryuuji and Taiga, and their relationship has been made built to be that of a parent and a child. Take into consideration that Ryuuji takes care of his mom, so when he meets Taiga, hears about her eating konbini food, sees no one else living at her house taking care of her, he assumes the role of her parent. He wakes her up, makes her breakfast and lunch, even sews together breast pads for her so she’ll fill in her swimsuit ’cause he doesn’t want her to fail! However Taiga is developing a thing for Ryuuji which means she’s falling for her parent-figure which basically means incest.
I think I could turn this into a whole “fascinating”(?) essay about exploring Japanese culture and individuality and the anime trope about being without parents and seeing the person living away from their parents as someone to look up to and go into how Tonagura at least had the decency to think up of some bullshit for that (bullshit that involved Fujikei, mind you), but lol effort.

personally, i don’t think taiga and ryuuji are in a parent-sort-of relationship – -b
more like brothers and sisters…i think D: