But it's a flavor off, and doesn't come to (your) mind immediately. So I asked instead of just throwing it out there as (yet another) half-cooked translation. I'm leaning away from "clench" because as best I can tell "kyun" is pretty much only used for positive feelings. And I think "clench" makes Shiori look conflicted rather than charmed. I kicked around "Sweet" but that could get confused for Shiori declaring victory in the "Dude Where's My Car; Dude! Sweet!" sense of "sweet." "She's so sweet" makes it look to impersonal/observational
Ba-dump it is. (also touching up Shiori's text in frame 4)