Tsumugi is a daily or working kimono that is woven by unevenly spun silk thread.
It's popular as a daily wear or street cloth (townwear) now.
It's worn for daily life, going out, and so on.
It's equivalent to denim of Western clothes.
At first, it was a farmer's daily or working clothes in Edo period.
The position improves with the age, and we wearing Tsumugi as a casual townwear now.
But still it is considered to casual, even if it is very expensive and high-quality.
In the Tenpou period [1830-1843] of Edo-age [1603-1867], the Tokugawa Shogunate government prohibited an extravagance.
And production and wearing the silk kimono were prohibited too.
According to one view, at that time,
because Tsumugi is woven by waste silk thread, and looks like cotton,
the government permitted only Tsumugi as a silk kimono, and it became popular.
Some fashionable people in Edo found Tsumugi is chic.
It's very durable and requiring a lot of time and effort to make it.
Now, Tsumugi is usually sold in a high-price.
(Only when men wear Tsumugi with family crest, it will be formal wear.)