*Disclaimer: My info comes solely from poking around Kiwaya's Japanese site, as I'm planning to buy a Japan-made ukulele when I visit Tokyo in March. I read Japanese.*
First of all, Kiwaya is a brand used by the Kiwaya company for the ukuleles they sell outside Japan. In Japan, you won't find a "Kiwaya" branded ukulele. Instead, Kiwaya sells all kinds of ukuleles, including those from other makers in addition to their 3 in-house brands:
1) FAMOUS
Ukuleles under the "Famous" brand are considered beginner ukes. Not because they're low quality but because they are laminates. The craftsmanship is still Japanese-quality, with attention to detail. Most Japanese people starting out buy a Famous uke. I believe this is what most people refer to when they talk about Kiwaya laminates.
2) F
Considered the high-end brand of the "Famous" line because the entire lineup is made of solid wood.
3) Luna
Totally different brand from "Luna Guitars." The brand has changed ownership through the years until it came under Kiwaya in the late nineties. Their lineup is also all solid-wood.
Kiwaya's Japanese website:
http://www.kiwayasbest.com/
Hope that helps.
(Just as a side note, I'm also interested in getting a Japan-made ukulele because based on my experience with Japanese craftsmanship, their quality is precise and top-notch. Their products may be more expensive but you really do get what you pay for. Not that craftsmen from other countries don't make good products, but in general there is some variation...you might get a totally awesome ukulele but if you're unlucky you might get a lemon. In Japan the odds of getting a lemon are fairly low. They're also really good at making products that feel good and easy to use. This applies not only to ukuleles but products in general)