Interesting idea, but I do have a few questions. 

When the human enters the town, a crystal is created, but what happens? Does it manifest and the human keeps it until he falls in love, or is it given to 'the one' upon creation and they have to find each other?

You mentioned weapons, defense, and magic. Are we defending this town from something or someone? Do we create our own enemies(or evil) to defeat? I can't imagine something happening to a precious jewel in the humdrum of everyday life around town.

Collars. Do humans enter town with one, or are they purchased or already owned by the neko and humans just attach their jewels to it? From what you wrote it seems like collars are more of an engagement gift from a human to a neko.