I think if it didn't have this twist Ai would end up married to the baldie guy (idk his name). Because up until the last minute Yuzu was not going to go to her until he found out they are not related.
since this is shoujo and not a mature one it is only natural to assume that this won't be a real incest story (i thought that at the beginning) I assumed that it would later on be revealed that he was adopted. I just find it convenient that it was in such a desperate situation that the truth was revealed. A sadist part of me wish the truth hadn't been revealed and they both stick with the decision they made. I mean if they both loved each other as much as they supposedly did why does it matter if they were brothers and sister, why break up in the first place and consciously decide to live their lives without each other in it?
I expected this plot twist but i was hoping it didn't happen but at the same time that seemed like the only way the story was heading. Am i the only one who is pissed at the mom after reading ch. 36.