How Could Girls Possibly Like Me?

What if you had a younger sister?

But then a whole bunch of girls show up around you...

"Then just be my boyfriend!" Why would the academy idol's young lady make such a declaration?

"Youyi, he's my dad." Why does the childhood friend look so pained?

"Youyi-chan, can I still keep loving you from now on?" Why are the eyes of the girl who's like a little sister getting misty?