The first question is “Why do that?” Humans already have a system for providing balance. We’ve got a butt. Humans are, AFAIK, the only bipedal creatures without significant horizontal extensions (like ducks, geese, and other birds) who maintain their upright balance for long periods of time without using a tail. we have outrageously large and strong muscles to keep us upright, chiefly the gluteus maximus. We try to characterize ourselves as The Animal that Thinks or The Animal that Laughs, but in reality, Man is the Animal With a Butt.
Clearly one reason is That They Can. And I have to admit that it is pretty cool – a computer-controlled, pneumatically activated articulated tail to maintain balance. The “inspired by a seahorse” part is obviously about the structure – seahorses don’t need a tail to maintain balance.
The report says that it’s for people who need help balancing – the injured, elderly, and infirm. And this is a Noble Cause, but I imagine people getting calls from their older relatives for help with these:
“Bob, grandma had to take off her tail to use the bathroom, and can’t get it back on again. Can you go over and help her put it back on?” I can also imagine older couples out walking together, hand in hand, and perhaps, tail entwined with tail.
I am stunned it doesn’t look more like a tentacle.
I understand it’s primarily for balance, but wouldn’t it be cool if you could also control it to manipulate your center of gravity in anticipation of a stunning acrobatic move, work as a prehensile fifth limb, or to communicate.
OK, I just Googled Japanese Tail. The only hits showing up are the device in the OP, more entries than you might imagine on how to translate Tail into Japanese, and then some recipes for preparing yellowtail.
Neat idea but I hope it’s lightweight, really light. In my experience (caring for zillions of the “elderly and infirm”) general frailty and loss of muscle strength often exceeds imbalance itself as the cause of falls and limited mobility (let alone the strokes, arthritis, neuropathy, and visual and cognitive impairment).