I did the same thing with my younger sister. I wonder if the older sister is just lying to herself so the younger one won't feel bad about going away/getting a higher education
I'll rejoice the day this gets translated again. Maybe now that it ended in Japan, a scanlator may find interest? Mangaplus might not do It anymore since it's finished.
I know Marino is supposed to be an adult since she's with Shin but..I can't help but see her as a little girl with those two tails, school uniform and baby-faced expressions.