Kao ni Denai Kashiwada-san to Kao ni Deru Oota-kun + - Vol. 2 Ch. 17 - Kashiwada-san and Her Big Brother's Memories

[MangaDex]

 

[Cream_cornet]

I kinda need the big sis and big bro to have their own spinoff series fr

 

[radiantmemories451]

Get together already.

 

[Hacete]

So this is where their siblings met. I thought they met in a different way in the main series