I love your level of detail and agree with @ Chiaki that I get an excellent picture of the girl’s everyday life and who she is.
But I would have liked to have another reference to the ring in the first 250 words. Maybe a little more explanation in the first paragraph, or later on. If I’m just looking at your first 250 words it feels a little disjointed. Like there’s mention of the ring at the beginning and I can tell it’s important but then we seem to lose focus on that and turn to the mom.
@Chiaki Ooooh I’m already loving the Xivlion characters and your MC’s voice too
“Agents in Xivlion always wear suits. There was probably some unspoken code about that.” He sounds kinda snarky.
My only suggestion is that your first sentence is a little awkward, maybe broken up too much? Maybe make his thought that you have in parenthesis a standalone sentence and finish the first sentence with how he feels to have been caught? Maybe something like “WHEN I CLICKED on the door to the local library and saw a group of agents guarding the Science and Technology section, my heart stopped.” ?