Summary: @IIMA_Hiroaki did a survey to figure out how people describe a certain way of sitting. The results are in, and even though there are still answers coming in, he made a map using ~1400 results.
Here's that map:
See that dude sitting at the top of the picture? That's the type of sitting that he's interested in. Here are the regional differences, in the same order as the image above:
- 体育座り = たいいくずわり = Tai-iku-zuwari
- 体操座り = たいそうすわり = Tai-sou-suwari
- 三角座り = さんかくすわり = San-kaku-suwari
- 安座 = あんざ = An-za
Let's break these down a little bit more.
- 体育座り is P.E. (体育) sitting (座り).
- 体操座り is gymnastics (体操) sitting (座り).
- 三角座り is triangle (三角) sitting (座り).
- 安座 is relaxed (安) sitting (座).
It's interesting to look at the different regions in Japan to see how they say different words in different ways. It's like how the U.S. will say "soda," "pop," "soda pop," "coke," etc depending on the location.
That being said, I don't know if we have a word for this kind of sitting in English. At least, I can't think of one.