I'm not familiar with Itaru or the A3! franchise, but I'm not entirely surprised that such a character exists elsewhere. The idea of a refined or regal-looking character having a sloppy hidden side has been around for a while, so it was a probably just matter of time before that secret was "video game addiction" for more than one character of that archetype.
As for it being a spoiler, in Shiori's context I feel like it's one of those "first episode"-spoilers, where it's hard to really keep it a secret even if I try to. (Especially now that Flowering Nightshade's game page immediately spoils it for Blooming Nightshade.)