TOKYO – We've all run out of smartphone juice during the day. The choice is usually to either lower the brightness level down to the point where we can barely see anything, to save energy, or buy one of those USB bricks to add instant power to your phone. 

The problem is that you usually have to charge up the brick first. 

Which is why I was so enamored with the easier solution, found on virtually every block of the city I visited recently, during a week in Japan. A $20 charger that didn't have to be plugged into the wall for power – it ran on four AA batteries. 

Perhaps Duracell and Energizer offer these products here. If so, they're nearly impossible to find on their websites or Amazon.com. But in Japan, where there's at least one 7-Eleven or other type of convenience store on every street of major cities, these type of chargers, powered by local company Panasonic, are front and center. 

Img 0147
Portable charger for smartphones, powered by AA batteries
Jefferson Graham

A week in Japan, and visits to the world's biggest (eight stories high) electronics shop highlighted tech tools that were useful, a little wacky and stuff I would lust over. 

The chargers fall into the useful category.

Legs
Panasonic Leg Air Massager
Panasonic

In the strange, weird and, maybe, "who knows" category, there were two products that caught my eye from Panasonic. The remote-controlled pink Leg Air Massager is targeted at women at work to wear stylishly under the desk. It is touted as being able to massage 12 parts of your feet and legs. This is something I've never seen in stores in the United States. 

If intrigued, you could buy one on eBay for just under $500, and that includes $100 for shipping. 

In the "what's next" category, try a cone-of-silence type of contraption that knocks out other sounds and other distractions while at work. 

Wear Space Main
Panasonic's Wear Space is a prototype for a new tool to keep office distractions at a minimum
Panasonic

WearSpace is a prototype for a product that might eventually come out. The idea is to block out noise from co-workers and distractions.

It’s a U-shaped fabric that wraps around the face, over some headphones. The phones block out noise, and the fabric obscures the view of what your co-workers are doing nearby.

No price has been announced, but I can tell you this: If you find wearing headphones a pain that can last for only a certain period of time, imagine how you’d feel with some fabric wrapped around your head.

Img 0556 1
Sony's Aromastic is a portable scent device
Jefferson Graham

I'm not a fan of  scents, but clearly many are. So for the man or woman who has everything, Sony is looking to bring instant aromas on the go in a package smaller than the original Walkman portable cassette players (remember those?). 

Like e-cigarettes, you charge up the USB-like device and fill it with cartridges for different scents. You can import these on eBay, for prices starting at around $50. 

Img 0527
Aibo, the robotic dog
Jefferson Graham

Another only-in-Japan Sony product, but not for long, is Aibo, the revived robotic dog that will roll over, walk over to be patted and do other pup tricks. The novelty item with a huge price tag – $2,899 – has been for sale in Japan this year and will be available in the U.S. in December. 

636537942213827003-tokyo-electronics.jpg
Said to be the world's biggest camera store, Yodobashi-Akiba in Tokyo, has 8 floors of electronics.
Jefferson Graham, USA TODAY

Meanwhile, those Japanese electronics shops! They are amazing places, way bigger than the ones we have back home, floor after floor of everything from cameras, phones and TVs to toilets, lighting and toys.

Beyond what’s new, what’s really cool is how the stores are so large; they don’t seem to get rid of old products.

Img 4097 1
Japan fax machines
Jefferson Graham

Want a fax machine? You can find a full assortment of models at the Yodibashi-Akiba shop. Remember mini-DV camcorders? I haven’t used one since 2010. But the store has several blank mini-DV cassettes available for sale.

Img 4080 1
Japan pay phone
Jefferson Graham

I even saw pay phones in Tokyo and Kobe, the two cities I visited. And even more striking, speaking of charging, many of the phones had charging booths right next to them. 

The gist is you put in some coins, open them up, and lock your phone in there while you go off and do whatever you have to do. When you come back and open it up, a recharged phone is waiting for you. 

Img 4081 1
Phone chargers in Japan
Jefferson Graham

Cool idea, but a big sayonara from me. I'm down with the $20 charger with the AA batteries. Who wants to lock up a phone for any time when Japan is awaiting you? 

Follow USA TODAY's Jefferson Graham (@jeffersongraham) on Twitter, Instagram and YouTube.