Home cookin': Soy milk hot pot

Here's something different. Soy milk hot pot. My girlfriend's friend sent it to her as a care package from Japan. I'm not sure of the origins, Japanese or Chinese or other. But I do know it has a oddly striking appearance. I'm used to sour cabbage hot pot, mala hot pot or other broths. But the broth on this is white. At first glance at a restaurant, prior to today, I didn't know what it was. My girlfriend enlightened me on it. So tonight after some time of wonder, I got to try it out. It turned out rather light in flavor and not really much of a soy milk taste. Which is good. Hot pot can sometimes be pretty heavy and oily, so this is a refreshing option. Add more vegetables and seafood, and less meat and it's a rather healthier and lighter feeling meal. If i'm in a hot pot restaurant next time and it's an option, I wouldn't mind trying it again. Anyone know where this soy milk version originated from?