I think it is because even during the theme park she was obviously seeing him as a cute kiddo
Maybe she always wanted to be a big sis
At first I thought she just liked being around children but the way the author keeps making her blush when he thinks of Iruma and the way Iruma keeps getting into sexual situations with her keep me second guessing.
Ara ara (▰˘◡˘▰)
I know it's def a little sus but I'm holding onto hope based on her viewing him as a kid from the first sight
We gotta hold on to the little things sometimes
I still don't know if Shiida's affection towards Iruma is a big sis / teacher way or romantic way. Hope it's just teacher love cuz she's way older than him, harem is acceptable but not that much.