I've been in the US for 14 years, and I have pretty much tried all of what this great country has to offer for the kitchen. As you remember, from Smart Lidz to vegetable-life-prolonging bags to cheap mandolins, I've experimented with many gadgets, and found them all very useless (and almost lost my thumb). But I guess the stand mixer is super great, which I don't think is sold in Japan (or if they are, I wouldn't be surprised they cost $1,500 a pop). Or the American sized jumbo oven (which I don't have currently) is great to cook large quantities, like a 20 pound turkey, roast vegetable, apple pie, and stuffing all at the same time.
Having said that, I haven't converted on two things (or I should say, I re-discovered the beauty and usefulness of them) in my kitchen. I think they are worth while.
1. Saran Wrap
Let me tell you, American saran wrap absolutely sucks. It's basically just a piece of plastic, nothing more. Glad's Cling Wrap is somewhat ok, but you can never compete with the quality of saran wrap from Japan.
Words can't explain the strength, durability, and stick-ability of Japanese saran wrap. you don't need Ziploc containers, you can just cover leftover dish or bowl of leftover food with a piece of wrap, and it's tightly covered, so no need to worry about its freshness the next day.
On top of this, the sizing is so smart. There are wide variety sizes available in Japan, but even here, there are long (regular size) and short ones. Short ones are perfect for covering small dishes. That's so Japanese, to not waste anything, even saran wrap!
Though it's about $5 per 20 meters (65 feet), which is a bit more expensive than the US brands, it's worth every penny!
2. Dish Washing Sponges
This is actually cheaper than any of the sponges you find here. Again, words cannot explain how great this is. The lacy outer with soft sponge inside keeps suds very very well. When you wash dishes, you want to have enough suds, and this is super perfect for it. It's very soft and won't scratch anything. Five of them for about $1.50. What a bargain!
You can buy these items at any of the Japanese grocery stores in the city. Trust me, they are worth trying.