idk much about it but cousin incest is super normalized in all manga. ive even seen it in straight japanese dramas. so idk what thats about
You can marry your cousin in Japan. My mom married my father who is her in-law/cousin, dad's also 10 years older. And we're a happy normal Asian family. So don't be too surprised.
I'd say it's to do with culture. At least in mine, it WAS normal. It's more frowned upon now. It used to be common because girls and boys, doesn't matter if they were cousins or not, were not allowed to be too friendly towards each other. So they grew up not feeling like they were cousins. So it wasn't as incesty in the sense they didn't see each other as siblings. Still weird though. But now that times have changed, we ourselves are now a lot closer to our cousins, so to us, it's gross. But not to the generation before us. Idk much about how it used to be in Japan, but I'd say they probably aren't as close to their relatives who aren't their immediate family. Or don't see each other as siblings, more like childhood friends I guess? That's my observation. I could be hella wrong so don't take my word for it. I was just trying to give a possible explanation as to why this is so normalized.
i dont know why that cousin is being such an annoying cockblocker. He should know better than having romantic feeling FOR a relative. There is a sea of men out there for you to choose from, and you go for your cousin? Sigh.
Also, if his character is only written to give rise to conflict, then Rui being a love rival would have been much better.