The huge jump in net worth is thanks to his Nintendo stock, which has tripled in the last year. It's almost as if his company did something very successful, right around the beginning of the last fiscal year. But what? Oh, if only we had some kind of handheld device we could carry around and do little brain exercises on, we'd be able to make these connections more easily. But it would have to be a nice looking gadget, and light; we're not going to carry around some bulky silver thing.