I've been coming to Kawaii gifts for years and years! One of the Japanese exchange students talked me into going when I was in college and I visit every time I'm in the area now. They were the first licensed SanX retailer in the US and that seems to drive a significant portion of their sales.
They are, as the name suggests, mainly a purveyor of cute Japanese products of many types, but they've branched out into the weird and cult type gifts too. You'll find everything from Rilakkuma to Ninjatown and other assorted oddities here.
For import goods they're usually a cycle behind. You can't expect to find things that are released in Japan for at least a few months. You also pay premium compared to what you would pay in Japan, but the prices are on par or cheaper than other US retailers.
The location is really good, an alley just off from Walnut St. This is the original location and the the only one I've been to.
The staff is usually friendly but not overly engaging. I prefer it that way, the shop is tiny and if staff was running around trying to offer people help when they don't need it, it would be chaos.