Just make and leave it. And there's no washing up to do! It's creamy and mild, and once you start making your own, you'll think that buying it makes no sense at all.
I've been making this nonstop ever since I learned how to make sour cream. I've made it so many times and thought I'd post the results of my experiments here!
If you want a soft cream, use 3 tablespoons of yoghurt. If you prefer it on the firm side, use 4-5 tablespoons.When you are making it, make sure you wash your hands first, so no bacteria gets in.
Enjoy Japanese food around the world.