there isnt any incest in the story, as far as we know. It's just feelings. None of it has been acted upon (yet at least).
She is not his real sister or yuri is just confuse he just admire or look up to his sister since he was little only this sister was close to him unlike other lunatic sister , so it's more like yuri is still young and cannot bear to see the sister who is kind to him get hurt.
She is more like cousine
uhm. they arent related tho? in the korean version yuri always calls her noona so thats why the translation says sister.
nvm i guess shes the cousin?
I wanna enjoy this story but the incest just doesn't let me idkkk I feel weird reading the story but i like yuri, ah decisions