Because he actually showed up in one panel in an earlier chapter. I think most people either forgot or didn’t notice it, but this chapter resolved his identity.
i would also describe my younger self like that my older brother was the coolest person around and was super nice. so whenever i got the chance i followed him around. i think rather than her liking her brother romantically shes just saying she loved him the most as a family member.
its pretty common for young girls to say they wanna marry their father or older sibling(in manga at least idk about real life)
EDIT:
read some other comments and like some of you guys spend too much time online sure some manga go that route but usually when the brother is already a main character not a unknown side char
i would also describe my younger self like that my older brother was the coolest person around and was super nice. so whenever i got the chance i followed him around. i think rather than her liking her brother romantically shes just saying she loved him the most as a family member.
its pretty common for young girls to say they wanna marry their father or older sibling(in manga at least idk about real life)
EDIT:
read some other comments and like some of you guys spend too much time online sure some manga go that route but usually when the brother is already a main character not a unknown side char
lost brain cells reading some of these comments. total melt down over nothing. and i thought i watched/read too much anime/manga.
like yeah almost every brocon/siscon ive seen in anime/manga has not been wholesome, im also not a dumbass and could see that this was not going in that direction.
live footage of me whenever I see the girl i have a crush on and might possibly like me back(yes im delusional) also get along with other guys(yes i need help)