Mid-August is Obon, so some restaurants won't be open during this period.
One kappo restaurant that I absolutely love is Shimokatsurachaya "Geppa":
* I love the seafood at this place. I don't think you'll have trouble booking dinner.
It's a bit more rustic in appearance than the restaurants you've mentioned; you can see the interior here: http://maps.google.com.au/maps?q=%E6%9C%88%E6%B3%A2&layer=c&z=17&sll=34.696110,135.497938&cid=4542088025790904097&panoid=Wci-FMrjf7XeglLb4XoTcw&cbp=13,224.07131184680171,,0,0&hl=en&ved=0CA8Q2wU&sa=X&ei=J5EcUIHSEs2OmQWp5YDoAg
If you want a more up-scale dining experience, I didn't mind the 3-Michelin-starred Koryu:
* Even if dinner is booked out, lunch should be really easy to get into.
I'm sure it's already too late to get into the ever-popular Masuda, but you might get lucky:
The following restaurants were mentioned in a local Osaka restaurant guide, and might be worth a try:
* Imamura: http://tabelog.com/osaka/A2701/A270105/27002646/
* Kaishoku Shimizu: http://tabelog.com/osaka/A2702/A270201/27015533/
* Konoha: http://tabelog.com/osaka/A2701/A270102/27007777/
* Yuno: http://tabelog.com/osaka/A2702/A270201/27015761/
There's also another restaurant, although it's not close to Osaka city (it's closer to the airport):
* Kasho: http://tabelog.com/osaka/A2705/A27050...
Kahala definitely fits the bill. It's difficult to classify that restaurant.
They highlight Japanese ingredients. The dishes have a minimalist, austere restraint about them and the wine is selected to take the back seat to the food. There's a kind-of "hassun" plate near the beginning, and tea near the end. These might be Japanese traits.
But the presentation of the meal, and the use of non-typical Japanese ingredients, points to something more original.
You might also want to try "kamoshiya Kusumoto." It seems to be well-regarded online:
Here's the interior:
I haven't been to Kigawa, nor Kigawa Asai.
But Kigawa is on my list, for three reasons:
1) the a-la-carte menu, as you've mentioned (with 100-150 items, it would take me forever to read them)
2) the fact that Kigawa touts itself as "naniwa-kappo," Kigawa Asai as "osaka-ryori," and I get the impression from the look and feel that it really does try to bring some local colour to the ambience
3) it was the place which trained the chef from Koryu, who also tries to use local Osakan ingredients and make Osakan references in his food (the sashimi platter at Koryu is called a "garden of fish," which is pronounced "naniwa": a pun on the old name for Osaka). I rather liked Koryu as I've said.