Japan has long harvested a shrub called mitsumata for its money supply. But when mitsumata started dying out, Japan frantically searched for alternatives to make yen.

It found a lifeline in the foothills of the Himalayas. A low-value crop called argeli grew abundantly and served as a perfect replacement for mitsumata.

Argeli was worth very little, often the only option for farmers who'd lost their crops to wild animals. When the Japanese arrived, they turned the once low-value argeli into a cash crop.

Now, one of Asia's poorest countries is growing the money for one of Asia's richest nations. And the influx of cash brought industry and investment to Nepal's small villages.

But while Japan loves its physical yen now, what will happen to Nepal's new big business if the country goes cashless like the rest of Asia?