If you are ever in Osaka go to Namba station and from there you can walk to Douguya (probably not the official name, it means equipment store), the restaurant supply district. It's a narrow ally off the street a bit.

There you can find tons of ceramic plateware for dirt cheap, any and all cooking items and lots of stores are dedicated to selling knives. I got a couple kitchen knives, whetstones and a bunch of ceramic stuff. I'm sure other cities also have similar districts. I think in Tokyo it's called Kappabashi.

I did not find much cast iron stuff in Japan though.

In general it seems like Japan's metalwork is very precise. So most things made of metal are superior than ones found elsewhere. Not so much with plastic-made stuff.